diff --git a/example/brainfuck/x86_compile.cpp b/example/brainfuck/x86_compile.cpp
index 27c3313d..ece58c56 100644
--- a/example/brainfuck/x86_compile.cpp
+++ b/example/brainfuck/x86_compile.cpp
@@ -23,8 +23,8 @@
 
 
 //
-// PE関連の構造体
-// <windows.h> からコピペ
+// PE structs
+//   Copy an Paste from <windows.h>
 //
 typedef unsigned long       DWORD;
 typedef int                 BOOL;
@@ -133,21 +133,21 @@ typedef struct _IMAGE_SECTION_HEADER {
 
 
 //
-// 出力バイナリサイズ
+// binary size for output
 //
 #ifndef BRAINFUCK_BINARY_SIZE
 #	define BRAINFUCK_BINARY_SIZE (16 * 1024)
 #endif
 
 //
-// ループ制限
+// loop limit
 //
 #ifndef BRAINFUCK_LOOP_LIMIT
 #	define BRAINFUCK_LOOP_LIMIT 256
 #endif
 
 //
-// 入力ファイル名
+// source file name
 //
 #ifndef BRAINFUCK_SOURCE_FILE
 #	define BRAINFUCK_SOURCE_FILE a.bf
@@ -155,7 +155,7 @@ typedef struct _IMAGE_SECTION_HEADER {
 
 
 //
-// 定数
+// constants
 //
 SPROUT_STATIC_CONSTEXPR std::size_t bin_size = BRAINFUCK_BINARY_SIZE;
 
@@ -171,7 +171,7 @@ SPROUT_STATIC_CONSTEXPR std::int32_t addr_buf = 0x00406000;
 
 
 //
-// 出力用関数
+// output functions
 //
 template<typename OutputIterator, typename T>
 SPROUT_CXX14_CONSTEXPR std::size_t
@@ -384,7 +384,7 @@ write_idata(OutputIterator& out, std::size_t n = 0) {
 	SPROUT_CONSTEXPR int idt[] = {
 		// IDT 1
 		0x5028, 0, 0, 0x5034, 0x5044,
-		// IDT (終端)
+		// IDT (end)
 		0, 0, 0, 0, 0
 	};
 	n += ::write_bytes(
@@ -392,7 +392,7 @@ write_idata(OutputIterator& out, std::size_t n = 0) {
 		idt
 		);
 
-	SPROUT_CONSTEXPR int ilt_iat[]  = {
+	SPROUT_CONSTEXPR int ilt_iat[] = {
 		0x5050, 0x505a, 0
 	};
 
@@ -429,12 +429,12 @@ write_idata(OutputIterator& out, std::size_t n = 0) {
 }
 
 //
-// コンパイル
+// compile
 //
 template<std::size_t LoopLimit = 256, typename InputIterator, typename RandomAccessIterator>
 SPROUT_CXX14_CONSTEXPR std::size_t
 compile(InputIterator first, InputIterator last, RandomAccessIterator& out_first) {
-	sprout::array<int, LoopLimit> loops {{}};	// ループを保存するスタック
+	sprout::array<int, LoopLimit> loops {{}};	// loop stack
 	auto loop_first = sprout::begin(loops);
 	auto loop_last = sprout::end(loops);
 	auto loop = loop_first;
@@ -499,12 +499,12 @@ compile(InputIterator first, InputIterator last, RandomAccessIterator& out_first
 				break;
 			case '[':
 				SPROUT_ASSERT_MSG(loop != loop_last, "loop overflow");
-				*loop++ = idx;	// インデックスをスタックに積む
+				*loop++ = idx;	// push index to stack
 				idx += ::write_bytes(
 					out,
 					(unsigned char)0x80, (unsigned char)0x3c, (unsigned char)0x0f, (unsigned char)0x00,	// cmp byte [edi+ecx],0
-					(unsigned char)0x0f, (unsigned char)0x84,											// jz 対応する]の直後
-					(unsigned char)0xde, (unsigned char)0xad, (unsigned char)0xbe, (unsigned char)0xef	// （アドレスは後で決定）
+					(unsigned char)0x0f, (unsigned char)0x84,											// jz (immediately after corresponding ']')
+					(unsigned char)0xde, (unsigned char)0xad, (unsigned char)0xbe, (unsigned char)0xef	// (set address later)
 					);
 				break;
 			case ']':
@@ -518,7 +518,7 @@ compile(InputIterator first, InputIterator last, RandomAccessIterator& out_first
 				auto out_loop = out_first + (idx_loop + 6);
 				::write_bytes(
 					out_loop,
-					(std::int32_t)(idx - (idx_loop + 10))												// （アドレス）
+					(std::int32_t)(idx - (idx_loop + 10))												// (address)
 					);
 				break;
 			}
@@ -528,7 +528,7 @@ compile(InputIterator first, InputIterator last, RandomAccessIterator& out_first
 
 	SPROUT_ASSERT_MSG(loop == loop_first, "missing ']'");
 
-	// 終了処理
+	// end
 	idx += ::write_bytes(
 		out,
 		(unsigned char)0x5f,																			// pop edi
@@ -540,15 +540,15 @@ compile(InputIterator first, InputIterator last, RandomAccessIterator& out_first
 }
 
 //
-// ビルド
+// build
 //
 template<std::size_t LoopLimit = 256, typename InputIterator, typename RandomAccessIterator>
 SPROUT_CXX14_CONSTEXPR std::size_t
 build(InputIterator first, InputIterator last, RandomAccessIterator& out) {
 	std::size_t n = 0;
-	n += ::write_pe_header(out, n);					// ヘッダ出力
-	n += ::write_idata(out, n);						// .idataセクション出力
-	n += ::compile<LoopLimit>(first, last, out);	// コンパイル
+	n += ::write_pe_header(out, n);					// header
+	n += ::write_idata(out, n);						// .idata section
+	n += ::compile<LoopLimit>(first, last, out);	// compile
 	return n;
 }
 
diff --git a/example/lifegame/main.cpp b/example/lifegame/main.cpp
index 27793060..966c0412 100644
--- a/example/lifegame/main.cpp
+++ b/example/lifegame/main.cpp
@@ -186,7 +186,7 @@ void SPROUT_NON_CONSTEXPR print_board(Container const& board) {
 int main() {
 	typedef sprout::array<sprout::array<int, BOARD_WIDTH>, BOARD_HEIGHT> board_type;
 
-	// セルの初期配置
+	// cell initial placement
 #define _ 0
 #define X 1
 	SPROUT_STATIC_CONSTEXPR board_type board0
@@ -211,10 +211,10 @@ int main() {
 #undef _
 #undef X
 
-	// ライフゲームの実行
+	// execute life game
 	SPROUT_STATIC_CONSTEXPR auto boards = ::next_cells<BOARD_COUNT>(board0);
 
-	// 表示
+	// print
 	for (auto&& board : boards) {
 		::print_board(board);
 	}
diff --git a/example/perceptron/g3.cpp b/example/perceptron/g3.cpp
index e49415b5..bce924c2 100644
--- a/example/perceptron/g3.cpp
+++ b/example/perceptron/g3.cpp
@@ -27,33 +27,33 @@ public:
 private:
 	struct worker {
 	public:
-		// 入力
+		// in
 		sprout::array<value_type, In + 1> xi1;
 		sprout::array<value_type, Hid + 1> xi2;
 		sprout::array<value_type, Out> xi3;
-		// 出力
+		// out
 		sprout::array<value_type, In + 1> o1;
 		sprout::array<value_type, Hid + 1> o2;
 		sprout::array<value_type, Out> o3;
 	};
 private:
-	// 誤差
+	// error
 	sprout::array<value_type, Hid + 1> d2;
 	sprout::array<value_type, Out> d3;
-	// 重み
+	// weight
 	sprout::array<value_type, (In + 1) * Hid> w1;
 	sprout::array<value_type, (Hid + 1) * Out> w2;
 private:
-	// 順伝播
+	// forward propagation
 	template<typename ForwardIterator>
 	SPROUT_CXX14_CONSTEXPR void
 	forward_propagation(ForwardIterator in_first, ForwardIterator in_last, worker& work) const {
-		// 入力層の順伝播
+		// forward propagation with input layer
 		sprout::copy(in_first, in_last, sprout::begin(work.xi1));
 		work.xi1[In] = 1;
 		sprout::copy(sprout::begin(work.xi1), sprout::end(work.xi1), sprout::begin(work.o1));
 
-		// 隠れ層の順伝播
+		// forward propagation with hidden layer
 		for (std::size_t i = 0; i != Hid; ++i) {
 			work.xi2[i] = 0;
 			for (std::size_t j = 0; j != In + 1; ++j) {
@@ -63,7 +63,7 @@ private:
 		}
 		work.o2[Hid] = 1;
 
-		// 出力層の順伝播
+		// forward propagation with output layer
 		for (std::size_t i = 0; i != Hid; ++i) {
 			work.xi3[i] = 0;
 			for (std::size_t j = 0; j != In + 1; ++j) {
@@ -80,9 +80,9 @@ public:
 		, w2(sprout::random::generate_array<(Hid + 1) * Out>(rng, sprout::random::uniform_01<value_type>()))
 	{}
 
-	// ニューラルネットの訓練
-	//	[in_first, in_last)	: 訓練データ (N*In 個)
-	//	[t_first, t_last)	: 教師データ (N 個)
+	// training of neural network
+	//	[in_first, in_last)	: training data (N*In elements)
+	//	[t_first, t_last)	: training data (N elements)
 	template<typename ForwardIterator1, typename ForwardIterator2>
 	SPROUT_CXX14_CONSTEXPR void
 	train(
@@ -99,24 +99,24 @@ public:
 			ForwardIterator1 in_it = in_first;
 			ForwardIterator2 t_it = t_first;
 			for (; in_it != in_last; sprout::advance(in_it, In), ++t_it) {
-				// 順伝播
+				// forward propagation
 				forward_propagation(in_it, sprout::next(in_it, In), work);
 
-				// 出力層の誤差計算
+				// error calculation of output layer
 				for (std::size_t i = 0; i != Out; ++i) {
 					d3[i] = *t_it == i ? work.o3[i] - 1
 						: work.o3[i]
 						;
 				}
 
-				// 出力層の重み更新
+				// weight update of output layer
 				for (std::size_t i = 0; i != Hid + 1; ++i) {
 					for (std::size_t j = 0; j != Out; ++j) {
 						w2[i * Out + j] -= eta * d3[j] * work.o2[i];
 					}
 				}
 
-				// 隠れ層の誤差計算
+				// error calculation of hidden layer
 				for (std::size_t i = 0; i != Hid + 1; ++i) {
 					d2[i] = 0;
 					for (std::size_t j = 0; j != Out; ++j) {
@@ -125,7 +125,7 @@ public:
 					d2[i] *= sprout::math::d_sigmoid(work.xi2[i]);
 				}
 
-				// 隠れ層の重み更新
+				// weight update of hidden layer
 				for (std::size_t i = 0; i != In + 1; ++i) {
 					for (std::size_t j = 0; j != Hid; ++j) {
 						w1[i * Hid + j] -= eta * d2[j] * work.o1[i];
@@ -135,7 +135,7 @@ public:
 		}
 	}
 
-	// 与えられたデータに対して最も可能性の高いクラスを返す
+	// returns to predict the most likely class for a given data
 	template<typename ForwardIterator>
 	SPROUT_CXX14_CONSTEXPR std::size_t
 	predict(ForwardIterator in_first, ForwardIterator in_last) const {
@@ -143,10 +143,10 @@ public:
 
 		worker work{};
 
-		// 順伝播による予測
+		// prediction by forward propagation
 		forward_propagation(in_first, in_last, work);
 
-		// 出力が最大になるクラスを判定
+		// determining a class which output is maximum
 		return sprout::distance(
 			sprout::begin(work.o3),
 			sprout::max_element(sprout::begin(work.o3), sprout::end(work.o3))
@@ -161,11 +161,11 @@ public:
 #include <sprout/random/unique_seed.hpp>
 #include <sprout/static_assert.hpp>
 
-// 訓練データ
+// training data
 SPROUT_CONSTEXPR auto train_data = sprout::make_array<double>(
 #	include "g3_train.csv"
 	);
-// 教師データ
+// teaching data
 SPROUT_CONSTEXPR auto teach_data = sprout::make_array<std::size_t>(
 #	include "g3_teach.csv"
 	);
@@ -173,17 +173,17 @@ SPROUT_CONSTEXPR auto teach_data = sprout::make_array<std::size_t>(
 SPROUT_STATIC_ASSERT(train_data.size() % 2 == 0);
 SPROUT_STATIC_ASSERT(train_data.size() / 2 == teach_data.size());
 
-// 訓練済みパーセプトロンを生成
+// generate a trained perceptron
 template<typename FloatType, std::size_t In, std::size_t Hid, std::size_t Out>
 SPROUT_CXX14_CONSTEXPR ::perceptron<FloatType, In, Hid, Out>
 make_trained_perceptron() {
-	// 乱数生成器
+	// random number generator
 	sprout::random::default_random_engine rng(SPROUT_UNIQUE_SEED);
 
-	// パーセプトロン
+	// perceptron
 	::perceptron<FloatType, In, Hid, Out> per(rng);
 
-	// 訓練
+	// training
 	per.train(
 		train_data.begin(), train_data.end(),
 		teach_data.begin(), teach_data.end(),
@@ -194,10 +194,10 @@ make_trained_perceptron() {
 }
 
 int main() {
-	// パーセプトロンを生成（入力2 隠れ3 出力3）
+	// generate a Perceptron (input 2, hidden 3, output 3)
 	SPROUT_CXX14_CONSTEXPR auto per = ::make_trained_perceptron<double, 2, 3, 3>();
 
-	// 結果の表示
+	// print results
 	for (auto it = train_data.begin(), last = train_data.end(); it != last; it += 2) {
 		std::cout << per.predict(it, it + 2) << std::endl;
 	}
diff --git a/libs/net/test/endian.cpp b/libs/net/test/endian.cpp
index 0edf85ec..5c27050d 100644
--- a/libs/net/test/endian.cpp
+++ b/libs/net/test/endian.cpp
@@ -16,31 +16,31 @@
 #include <testspr/tools.hpp>
 
 namespace testspr {
-    static void endian_test() {
-        using namespace sprout;
+	static void endian_test() {
+		using namespace sprout;
 
-        { // 16
-            TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint16_t(0x0A1B)) == std::uint16_t(0x1B0A));
-            TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint16_t(0x1B0A)) == std::uint16_t(0x0A1B));
-            TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint16_t(0x0A1B)) == std::uint16_t(0x1B0A));
-            TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint16_t(0x1B0A)) == std::uint16_t(0x0A1B));
-        }
+		{	// 16
+			TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint16_t(0x0A1B)) == std::uint16_t(0x1B0A));
+			TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint16_t(0x1B0A)) == std::uint16_t(0x0A1B));
+			TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint16_t(0x0A1B)) == std::uint16_t(0x1B0A));
+			TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint16_t(0x1B0A)) == std::uint16_t(0x0A1B));
+		}
 
-        { // 32
-            TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint32_t(0x0A1B2C3D)) == std::uint32_t(0x3D2C1B0A));
-            TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint32_t(0x3D2C1B0A)) == std::uint32_t(0x0A1B2C3D));
-            TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint32_t(0x0A1B2C3D)) == std::uint32_t(0x1B0A3D2C));
-            TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint32_t(0x1B0A3D2C)) == std::uint32_t(0x0A1B2C3D));
-        }
+		{	// 32
+			TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint32_t(0x0A1B2C3D)) == std::uint32_t(0x3D2C1B0A));
+			TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint32_t(0x3D2C1B0A)) == std::uint32_t(0x0A1B2C3D));
+			TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint32_t(0x0A1B2C3D)) == std::uint32_t(0x1B0A3D2C));
+			TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint32_t(0x1B0A3D2C)) == std::uint32_t(0x0A1B2C3D));
+		}
 
-        { // 64
-            TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint64_t(0x0A1B2C3D4E5F6A7B)) == std::uint64_t(0x7B6A5F4E3D2C1B0A));
-            TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint64_t(0x7B6A5F4E3D2C1B0A)) == std::uint64_t(0x0A1B2C3D4E5F6A7B));
-            TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint64_t(0x0A1B2C3D4E5F6A7B)) == std::uint64_t(0x1B0A3D2C5F4E7B6A));
-            TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint64_t(0x1B0A3D2C5F4E7B6A)) == std::uint64_t(0x0A1B2C3D4E5F6A7B));
-        }
-    }
-}   // namespace testspr
+		{	// 64
+			TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint64_t(0x0A1B2C3D4E5F6A7B)) == std::uint64_t(0x7B6A5F4E3D2C1B0A));
+			TESTSPR_ASSERT(sprout::net::detail::reverse(std::uint64_t(0x7B6A5F4E3D2C1B0A)) == std::uint64_t(0x0A1B2C3D4E5F6A7B));
+			TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint64_t(0x0A1B2C3D4E5F6A7B)) == std::uint64_t(0x1B0A3D2C5F4E7B6A));
+			TESTSPR_ASSERT(sprout::net::detail::reverse_words(std::uint64_t(0x1B0A3D2C5F4E7B6A)) == std::uint64_t(0x0A1B2C3D4E5F6A7B));
+		}
+	}
+}	// namespace testspr
 
 #ifndef TESTSPR_CPP_INCLUDE
 #	define TESTSPR_TEST_FUNCTION testspr::endian_test
diff --git a/libs/string/example/literals_to_string.cpp b/libs/string/example/literals_to_string.cpp
index 7aad1c08..2c2f97b0 100644
--- a/libs/string/example/literals_to_string.cpp
+++ b/libs/string/example/literals_to_string.cpp
@@ -17,7 +17,7 @@
 
 int
 main(){
-	
+
 	//
 	// String literal to Sprout.String
 	//
@@ -30,7 +30,7 @@ main(){
 		static_assert(str2 == L"縺ｻ繧�縺ｻ繧�", "");
 		static_assert(std::is_same<decltype(str2), sprout::wstring<4> const>{}, "");
 	}
-	
+
 	//
 	// Integer literal to Sprout.String
 	//
@@ -38,7 +38,7 @@ main(){
 		static constexpr auto str = sprout::to_string(42);
 		static_assert(str == "42", "");
 	}
-	
+
 	//
 	// Float literal to Sprout.String
 	//
diff --git a/libs/weed/example/__TIME__.cpp b/libs/weed/example/__TIME__.cpp
index 26ec1eab..17536a2b 100644
--- a/libs/weed/example/__TIME__.cpp
+++ b/libs/weed/example/__TIME__.cpp
@@ -28,7 +28,7 @@ main(){
 	// __TIME__ to Sprout.String
 	//
 	static constexpr auto time = sprout::to_string(__TIME__);
-// 	static constexpr auto time = sprout::to_string("23:22:45");
+//	static constexpr auto time = sprout::to_string("23:22:45");
 	
 
 	//
@@ -43,13 +43,13 @@ main(){
 	// get result
 	//
 	static constexpr sprout::array<long long int, 3> result_attr = result.attr();
-	static constexpr auto hour    = result_attr[0];
+	static constexpr auto hour   = result_attr[0];
 	static constexpr auto minute = result_attr[1];
-	static constexpr auto second  = result_attr[2];
+	static constexpr auto second = result_attr[2];
 
-// 	static_assert(hour   == 23, "");
-// 	static_assert(minute == 22, "");
-// 	static_assert(second == 45, "");
+//	static_assert(hour   == 23, "");
+//	static_assert(minute == 22, "");
+//	static_assert(second == 45, "");
 
 	std::cout << hour << std::endl;
 	std::cout << minute << std::endl;
diff --git a/sprout/compost/sources/source.hpp b/sprout/compost/sources/source.hpp
index f0d3bddc..639e268c 100644
--- a/sprout/compost/sources/source.hpp
+++ b/sprout/compost/sources/source.hpp
@@ -34,13 +34,13 @@ namespace sprout {
 			//
 			struct info_type {
 			public:
-				std::uint16_t format_tag;		// フォーマットID
-				std::uint16_t channels;			// チャンネル数
-				std::uint32_t samples_per_sec;	// サンプリングレート
-				std::uint32_t bytes_per_sec;	// データ速度 (Byte/sec)
-				std::uint16_t block_size;		// ブロックサイズ (Byte/sample*チャンネル数)
-				std::uint16_t bits_per_sample;	// サンプルあたりのビット数 (bit/sample)
-				std::size_t size;				// 要素数
+				std::uint16_t format_tag;		// format ID
+				std::uint16_t channels;			// channels
+				std::uint32_t samples_per_sec;	// sampling rate
+				std::uint32_t bytes_per_sec;	// data speed (Byte/sec)
+				std::uint16_t block_size;		// block size (Byte/sample*channels)
+				std::uint16_t bits_per_sample;	// bits per sample (bit/sample)
+				std::size_t size;				// elements
 			};
 			//
 			// sound_type
diff --git a/sprout/compost/utility/rosenberg.hpp b/sprout/compost/utility/rosenberg.hpp
index b9c9b7d3..1b5cc4d6 100644
--- a/sprout/compost/utility/rosenberg.hpp
+++ b/sprout/compost/utility/rosenberg.hpp
@@ -16,7 +16,9 @@ namespace sprout {
 	namespace compost {
 		//
 		// rosenberg_value
-		//	Rosenberg 波は，声門開大期と閉小期が周期の40%，16%となる非対称形の波形であり，τ1 が開大期，τ2が閉小期を示す．
+		//   Rosenberg wave is asymmetric waveform,
+		//   expansion period/reduction period of the glottis is 40%/16% of the cycle,
+		//   tau1 is expansion period, tau2 is reduction period
 		//
 		template<typename T>
 		inline SPROUT_CONSTEXPR typename sprout::float_promote<T>::type
diff --git a/sprout/cstdlib/abs.hpp b/sprout/cstdlib/abs.hpp
index 89c08488..7d870a0b 100644
--- a/sprout/cstdlib/abs.hpp
+++ b/sprout/cstdlib/abs.hpp
@@ -18,7 +18,7 @@
 
 namespace sprout {
 
-	// 7.20.6.1 abs，labs，及び llabs 関数
+	// 7.20.6.1 abs, labs, and llabs function
 	inline SPROUT_CONSTEXPR int
 	abs(int j) {
 		return j < 0 ? -j : j;
diff --git a/sprout/cstdlib/div.hpp b/sprout/cstdlib/div.hpp
index 0bf02507..a77bfa34 100644
--- a/sprout/cstdlib/div.hpp
+++ b/sprout/cstdlib/div.hpp
@@ -88,7 +88,7 @@ namespace sprout {
 		}
 	}	// namespace detail
 
-	// 7.20.6.2 div，ldiv，及び lldiv 関数
+	// 7.20.6.2 div, ldiv, and lldiv function
 	inline SPROUT_CONSTEXPR sprout::div_t
 	div(int numer, int denom) {
 		return sprout::detail::div_impl(numer, denom);
diff --git a/sprout/cstring/memchr.hpp b/sprout/cstring/memchr.hpp
index 2c6c854a..cfb40c80 100644
--- a/sprout/cstring/memchr.hpp
+++ b/sprout/cstring/memchr.hpp
@@ -50,7 +50,7 @@ namespace sprout {
 		}
 	}	// namespace detail
 
-	// 7.21.5.1 memchr 関数
+	// 7.21.5.1 memchr function
 	//
 	//	recursion depth:
 	//		O(log N)
diff --git a/sprout/cstring/memcmp.hpp b/sprout/cstring/memcmp.hpp
index b0178d09..9fc3f0db 100644
--- a/sprout/cstring/memcmp.hpp
+++ b/sprout/cstring/memcmp.hpp
@@ -27,7 +27,7 @@ namespace sprout {
 		}
 	}	// namespace detail
 
-	// 7.21.4.1 memcmp 関数
+	// 7.21.4.1 memcmp function
 	//
 	//	recursion depth:
 	//		O(log(N1+N2))
diff --git a/sprout/cstring/strchr.hpp b/sprout/cstring/strchr.hpp
index 176e1534..5ef83053 100644
--- a/sprout/cstring/strchr.hpp
+++ b/sprout/cstring/strchr.hpp
@@ -63,7 +63,7 @@ namespace sprout {
 
 	}	// namespace detail
 
-	// 7.21.5.2 strchr 関数
+	// 7.21.5.2 strchr function
 	//
 	//	recursion depth:
 	//		O(log N)
diff --git a/sprout/cstring/strcmp.hpp b/sprout/cstring/strcmp.hpp
index 2e6a70ae..99ae0642 100644
--- a/sprout/cstring/strcmp.hpp
+++ b/sprout/cstring/strcmp.hpp
@@ -76,7 +76,7 @@ namespace sprout {
 		}
 	}	// namespace detail
 
-	// 7.21.4.2 strcmp 関数
+	// 7.21.4.2 strcmp function
 	//
 	//	recursion depth:
 	//		O(log(N1+N2))
diff --git a/sprout/cstring/strcoll.hpp b/sprout/cstring/strcoll.hpp
index 87d8082c..39d66518 100644
--- a/sprout/cstring/strcoll.hpp
+++ b/sprout/cstring/strcoll.hpp
@@ -15,7 +15,7 @@
 
 namespace sprout {
 
-	// 7.21.4.3 strcoll 関数
+	// 7.21.4.3 strcoll function
 	//
 	//	recursion depth:
 	//		O(log(N1+N2))
diff --git a/sprout/cstring/strcspn.hpp b/sprout/cstring/strcspn.hpp
index efe95572..974da44c 100644
--- a/sprout/cstring/strcspn.hpp
+++ b/sprout/cstring/strcspn.hpp
@@ -66,7 +66,7 @@ namespace sprout {
 		}
 	}	// namespace detail
 
-	// 7.21.5.3 strcspn 関数
+	// 7.21.5.3 strcspn function
 	//
 	//	recursion depth:
 	//		O(log(N1+N2))
diff --git a/sprout/cstring/strlen.hpp b/sprout/cstring/strlen.hpp
index ead67f9e..be5c5b40 100644
--- a/sprout/cstring/strlen.hpp
+++ b/sprout/cstring/strlen.hpp
@@ -64,7 +64,7 @@ namespace sprout {
 		}
 	}	// namespace detail
 
-	// 7.21.6.3 strlen 関数
+	// 7.21.6.3 strlen function
 	//
 	//	recursion depth:
 	//		O(log N)
diff --git a/sprout/cstring/strncmp.hpp b/sprout/cstring/strncmp.hpp
index 41a3e782..42f0d344 100644
--- a/sprout/cstring/strncmp.hpp
+++ b/sprout/cstring/strncmp.hpp
@@ -17,7 +17,7 @@
 
 namespace sprout {
 
-	// 7.21.4.4 strncmp 関数
+	// 7.21.4.4 strncmp function
 	//
 	//	recursion depth:
 	//		O(log(N1+N2))
diff --git a/sprout/cstring/strpbrk.hpp b/sprout/cstring/strpbrk.hpp
index 6dd608f1..624ddcde 100644
--- a/sprout/cstring/strpbrk.hpp
+++ b/sprout/cstring/strpbrk.hpp
@@ -67,7 +67,7 @@ namespace sprout {
 		}
 	}	// namespace detail
 
-	// 7.21.5.4 strpbrk 関数
+	// 7.21.5.4 strpbrk function
 	//
 	//	recursion depth:
 	//		O(log(N1+N2))
diff --git a/sprout/cstring/strrchr.hpp b/sprout/cstring/strrchr.hpp
index a98560b6..3979c65b 100644
--- a/sprout/cstring/strrchr.hpp
+++ b/sprout/cstring/strrchr.hpp
@@ -74,7 +74,7 @@ namespace sprout {
 		}
 	}	// namespace detail
 
-	// 7.21.5.5 strrchr 関数
+	// 7.21.5.5 strrchr function
 	//
 	//	recursion depth:
 	//		O(log N)
diff --git a/sprout/cstring/strspn.hpp b/sprout/cstring/strspn.hpp
index 812efe29..d8d77a15 100644
--- a/sprout/cstring/strspn.hpp
+++ b/sprout/cstring/strspn.hpp
@@ -66,7 +66,7 @@ namespace sprout {
 		}
 	}	// namespace detail
 
-	// 7.21.5.6 strspn 関数
+	// 7.21.5.6 strspn function
 	//
 	//	recursion depth:
 	//		O(log(N1+N2))
diff --git a/sprout/cstring/strstr.hpp b/sprout/cstring/strstr.hpp
index 0250c579..6940ee4e 100644
--- a/sprout/cstring/strstr.hpp
+++ b/sprout/cstring/strstr.hpp
@@ -128,7 +128,7 @@ namespace sprout {
 		}
 	}	// namespace detail
 
-	// 7.21.5.7 strstr 関数
+	// 7.21.5.7 strstr function
 	//
 	//	recursion depth:
 	//		O(log(N1+N2))
diff --git a/tools/files/filegraph.cpp b/tools/files/filegraph.cpp
index 37a54c5a..7b29b9e1 100644
--- a/tools/files/filegraph.cpp
+++ b/tools/files/filegraph.cpp
@@ -34,7 +34,7 @@ class include_graph_hooks
 private:
 	typedef boost::wave::context_policies::default_preprocessing_hooks base_type;
 public:
-	// グラフのノード
+	// node of graph
 	struct node_type {
 		boost::filesystem::path absolute;
 		boost::filesystem::path filename;
@@ -99,7 +99,7 @@ public:
 	edges() const {
 		return edge_list_;
 	}
-	// グラフ生成
+	// make graph
 	template<typename Graph>
 	Graph make_graph() const {
 		return Graph(edge_list_.begin(), edge_list_.end(), node_list_.size());
@@ -107,7 +107,7 @@ public:
 	graph_type make_graph() const {
 		return make_graph<graph_type>();
 	}
-	// graphviz 出力
+	// output graphviz
 	void write_graphviz(std::ostream& out) const {
 		boost::write_graphviz(
 			out,
@@ -115,7 +115,7 @@ public:
 			boost::make_label_writer(&node_list_[0])
 		);
 	}
-	// 非インクルードガード検出
+	// collect no include guard files
 	template<typename OutputIterator>
 	void collect_no_include_guard_files(OutputIterator result) const {
 		std::copy_if(
@@ -123,7 +123,7 @@ public:
 			[](node_type const& e) { return !e.has_include_guard; }
 			);
 	}
-	// 循環インクルード検出
+	// collect circulated includes
 	template<typename OutputIterator>
 	void collect_circulated_includes(OutputIterator result) const {
 		boost::depth_first_search(
@@ -131,7 +131,7 @@ public:
 			boost::visitor(sprig::make_back_edge_recorder(result))
 			);
 	}
-	// 孤立ファイル検出
+	// collect isolated files
 	template<typename OutputIterator>
 	void collect_isolated_files(OutputIterator result, boost::filesystem::path const& path) const {
 		typedef boost::filesystem::recursive_directory_iterator iterator;
@@ -139,14 +139,14 @@ public:
 			if (!boost::filesystem::is_directory(*it)) {
 				boost::filesystem::path abspath(boost::filesystem::absolute(*it));
 				auto found = std::find(node_list_.begin(), node_list_.end(), abspath);
-				if (found == node_list_.end()) {	// インクルードされていないならば結果に追加
+				if (found == node_list_.end()) {	// add result if not include
 					*result++ = abspath.generic_string();
 				}
 			}
 		}
 	}
 public:
-	// インクルードファイルパス設定処理をフック
+	// hook the locate include file process
 	template<typename Context>
 	bool locate_include_file(
 		Context& ctx,
@@ -161,10 +161,10 @@ public:
 		if (!base_type::locate_include_file(ctx, file_path, is_system, current_name, dir_path, native_name)) {
 			return false;
 		}
-		dir_path = filename;	// インクルードディレクティブのテキストで上書き
+		dir_path = filename;	// overwrite the include directive text
 		return true;
 	}
-	// インクルードファイル解析開始をフック
+	// hook the opened include file process
 	template<typename Context>
 	void opened_include_file(
 		Context const& /*ctx*/,
@@ -176,20 +176,20 @@ public:
 		boost::filesystem::path abspath(boost::filesystem::absolute(absname));
 		auto found = std::find(node_list_.begin(), node_list_.end(), abspath);
 		auto to = std::distance(node_list_.begin(), found);
-		if (found == node_list_.end()) {	// 最初のインクルードならばノードに追加
+		if (found == node_list_.end()) {	// add node if first include
 			node_list_.emplace_back(abspath, relname);
 		}
 		edge_list_.emplace_back(current_list_.back(), to);
-		current_list_.push_back(to);	// カレントを更新
+		current_list_.push_back(to);	// update current
 		current_ = to;
 	}
-	// インクルードファイル解析完了をフック
+	// hook the returning from include file process
 	template<typename Context>
 	void returning_from_include_file(Context const& /*ctx*/) {
 		current_ = current_list_.back();
-		current_list_.pop_back();	// カレントを戻す
+		current_list_.pop_back();	// revert current
 	}
-	// インクルードガード検出をフック
+	// hook the detected include guard process
 	template<typename Context>
 	void detected_include_guard(
 		Context const& /*ctx*/,
@@ -210,7 +210,7 @@ public:
 	}
 };
 
-// システムインクルードパスの取得
+// collect sysinclude paths
 template<typename OutputIterator>
 void collect_sysinclude_paths(OutputIterator result, std::string const& command = "g++") {
 	{
@@ -224,7 +224,7 @@ void collect_sysinclude_paths(OutputIterator result, std::string const& command
 			std::istreambuf_iterator<char>()
 			);
 		auto rng = boost::make_iterator_range(text);
-		rng = sprig::find_skip(rng, boost::algorithm::first_finder("#include <...>"));	// インクルードパスの始点までスキップ
+		rng = sprig::find_skip(rng, boost::algorithm::first_finder("#include <...>"));	// skip to begin of the include path
 		rng = sprig::find_skip(rng, boost::algorithm::first_finder("\n"));
 		while (boost::algorithm::starts_with(rng, " ")) {
 			auto found = sprig::find_between(
@@ -247,7 +247,7 @@ int main(int argc, const char* argv[]) {
 	if (argc >= 2) {
 		src = argv[1];
 
-		// ファイルの内容を全部 text に読み込む
+		// read text from file
 		std::ifstream ifs(argv[1]);
 		text = std::string(
 			std::istreambuf_iterator<char>(ifs.rdbuf()),
@@ -259,7 +259,7 @@ int main(int argc, const char* argv[]) {
 	}
 
 	try {
-		// プリプロセッサを用意
+		// prepare preprocessor
 		typedef boost::wave::context<
 			std::string::iterator,
 			boost::wave::cpplexer::lex_iterator<boost::wave::cpplexer::lex_token<> >,
@@ -268,14 +268,14 @@ int main(int argc, const char* argv[]) {
 		> context_type;
 		context_type ctx(text.begin(), text.end(), src.c_str(), ::include_graph_hooks(src));
 
-		// ランゲージの設定
+		// set language
 		ctx.set_language(
 			boost::wave::language_support(
 				boost::wave::support_cpp11
-				| boost::wave::support_option_include_guard_detection	// インクルードガード検出
+				| boost::wave::support_option_include_guard_detection	// include guard detection
 				)
 			);
-		// インクルードパスの設定
+		// set include paths
 		if (!command.empty()) {
 			std::cout
 				<< "collect command :\n"
@@ -304,7 +304,7 @@ int main(int argc, const char* argv[]) {
 		}
 
 		if (!src.empty()) {
-			// プリプロセスを走らせる
+			// run preprocessor
 			for (auto&& e : ctx) {
 				//std::cout << e.get_value();
 			}
@@ -323,7 +323,7 @@ int main(int argc, const char* argv[]) {
 			std::vector<std::string> tokens;
 			boost::algorithm::split(tokens, line, boost::algorithm::is_space());
 			if (tokens.at(0) == "find") {
-				// インクルードファイルを検索
+				// find include paths
 				if (tokens.size() < 2) {
 					std::cout
 						<< "missing parameter.\n"
@@ -348,7 +348,7 @@ int main(int argc, const char* argv[]) {
 					<< std::flush
 					;
 			} else if (tokens.at(0) == "graph") {
-				// グラフ出力
+				// output graph
 				std::cout
 					<< "graph output > out.graph.dot\n"
 					;
@@ -358,7 +358,7 @@ int main(int argc, const char* argv[]) {
 					<< std::flush
 					;
 			} else if (tokens.at(0) == "noguard") {
-				// 非インクルードガードを出力
+				// output no include guarde files
 				std::vector<::include_graph_hooks::node_type> list;
 				ctx.get_hooks().collect_no_include_guard_files(std::back_inserter(list));
 				std::cout
@@ -373,7 +373,7 @@ int main(int argc, const char* argv[]) {
 					<< std::flush
 					;
 			} else if (tokens.at(0) == "circulated") {
-				// 循環インクルードを出力
+				// output circulated includes
 				std::vector<typename boost::graph_traits<::include_graph_hooks::graph_type>::edge_descriptor> list;
 				ctx.get_hooks().collect_circulated_includes(std::back_inserter(list));
 				auto g = ctx.get_hooks().make_graph();
@@ -390,12 +390,12 @@ int main(int argc, const char* argv[]) {
 					<< std::flush
 					;
 			} else if (tokens.at(0) == "isolated") {
-				// Sprout の孤立ファイルを出力
+				// output Sprout isolated files
 				std::cout
 					<< "isolated files output > out.isolated.txt\n"
 					;
 				std::ofstream ofs("out.isolated.txt");
-				// Sprout のシステムインクル−ドパスを取得
+				// get Sprout system include path
 				std::string filepath("sprout/config.hpp");
 				std::string dirpath;
 				if (!ctx.find_include_file(filepath, dirpath, true, 0)) {
@@ -406,7 +406,7 @@ int main(int argc, const char* argv[]) {
 					continue;
 				}
 				dirpath = boost::filesystem::path(filepath).parent_path().generic_string();
-				// リスト出力
+				// output list
 				std::vector<std::string> list;
 				ctx.get_hooks().collect_isolated_files(std::back_inserter(list), dirpath);
 				std::sort(list.begin(), list.end());
@@ -422,7 +422,7 @@ int main(int argc, const char* argv[]) {
 			}
 		}
 	} catch (boost::wave::cpp_exception& e) {
-		// プリプロセスでエラー発生
+		// eorror handling
 		std::cerr
 			<< "#error " << e.file_name() << "(" << e.line_no() << "):" << e.description() << "\n"
 			<< std::flush