diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 808f250..492a4f2 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -13,8 +13,8 @@ PRIVATE
     # Sources
     yycc/string/reinterpret.cpp
     yycc/string/op.cpp
-    yycc/string/stream.cpp
     yycc/patch/fopen.cpp
+    yycc/patch/stream.cpp
     yycc/rust/panic.cpp
     yycc/rust/env.cpp
     yycc/windows/com.cpp
@@ -31,10 +31,11 @@ PRIVATE
     yycc/carton/tabulate.cpp
     yycc/carton/ironpad.cpp
     yycc/carton/csconsole.cpp
-    yycc/carton/clap/option.cpp
-    yycc/carton/clap/variable.cpp
-    yycc/carton/clap/summary.cpp
-    yycc/carton/clap/application.cpp
+    #yycc/carton/clap/option.cpp
+    #yycc/carton/clap/variable.cpp
+    #yycc/carton/clap/summary.cpp
+    #yycc/carton/clap/application.cpp
+    #yycc/carton/clap/manual.cpp
 )
 target_sources(YYCCommonplace 
 PUBLIC
@@ -54,10 +55,10 @@ FILES
     yycc/flag_enum.hpp
     yycc/string/reinterpret.hpp
     yycc/string/op.hpp
-    yycc/string/stream.hpp
-    yycc/string/format.hpp
     yycc/patch/ptr_pad.hpp
     yycc/patch/fopen.hpp
+    yycc/patch/stream.hpp
+    yycc/patch/format.hpp
     yycc/num/parse.hpp
     yycc/num/stringify.hpp
     yycc/num/safe_cast.hpp
@@ -93,6 +94,7 @@ FILES
     yycc/carton/clap/variable.hpp
     yycc/carton/clap/summary.hpp
     yycc/carton/clap/application.hpp
+    yycc/carton/clap/manual.hpp
 )
 # Setup header infomations
 target_include_directories(YYCCommonplace
diff --git a/src/yycc/carton/clap/application.cpp b/src/yycc/carton/clap/application.cpp
index 2175eaa..32dc4a6 100644
--- a/src/yycc/carton/clap/application.cpp
+++ b/src/yycc/carton/clap/application.cpp
@@ -1,12 +1,12 @@
 #include "application.hpp"
 
-#define NS_YYCC_CLAP ::yycc::carton::clap
+#define CLAP ::yycc::carton::clap
 
 namespace yycc::carton::clap::application {
 
-    using Summary = NS_YYCC_CLAP::summary::Summary;
-    using OptionCollection = NS_YYCC_CLAP::option::OptionCollection;
-    using VariableCollection = NS_YYCC_CLAP::variable::VariableCollection;
+    using Summary = CLAP::summary::Summary;
+    using OptionCollection = CLAP::option::OptionCollection;
+    using VariableCollection = CLAP::variable::VariableCollection;
 
     Application::Application(Summary &&summary, OptionCollection &&options, VariableCollection &&variables) :
         summary(std::move(summary)), options(std::move(options)), variables(std::move(variables)) {}
diff --git a/src/yycc/carton/clap/application.hpp b/src/yycc/carton/clap/application.hpp
index 58c8ead..3690e30 100644
--- a/src/yycc/carton/clap/application.hpp
+++ b/src/yycc/carton/clap/application.hpp
@@ -2,6 +2,7 @@
 #include "summary.hpp"
 #include "option.hpp"
 #include "variable.hpp"
+#include "../../macro/class_copy_move.hpp"
 
 #define NS_YYCC_CLAP ::yycc::carton::clap
 
diff --git a/src/yycc/carton/clap/manual.cpp b/src/yycc/carton/clap/manual.cpp
new file mode 100644
index 0000000..c04b544
--- /dev/null
+++ b/src/yycc/carton/clap/manual.cpp
@@ -0,0 +1,69 @@
+#include "manual.hpp"
+#include "../termcolor.hpp"
+#include "../../patch/stream.hpp"
+#include "../../string/op.hpp"
+
+#define CLAP ::yycc::carton::clap
+#define TABULATE ::yycc::carton::tabulate
+#define TERMCOLOR ::yycc::carton::termcolor
+#define OP ::yycc::carton::op
+
+using namespace ::yycc::patch::stream;
+
+namespace yycc::carton::clap::manual::Manual {
+
+#pragma region Manual Translation
+
+    ManualTr::ManualTr() :
+        author_and_version(u8"Invented by {0}. Version {1}."), usage_title(u8"Usage:"), usage_body(u8"{0} <options> ..."),
+        avail_opt(u8"Available options:"), avail_var(u8"Available environment variables:") {}
+
+    ManualTr::~ManualTr() {}
+
+#pragma endregion
+
+#pragma region Manual
+
+    using Application = CLAP::application::Application;
+    using Tabulate = TABULATE::Tabulate;
+
+    Manual::Manual(const Application &app, ManualTr &&trctx) : trctx(std::move(trctx)), app(app), opt_printer(3), var_printer(2) {
+        this->setup_table();
+        this->fill_opt_table();
+        this->fill_var_table();
+    }
+
+    Manual::~Manual() {}
+
+    void Manual::setup_table() {
+        this->opt_printer.show_header(false);
+        this->opt_printer.show_bar(false);
+        this->opt_printer.set_prefix(u8"    ");
+
+        this->var_printer.show_header(false);
+        this->var_printer.show_bar(false);
+        this->var_printer.set_prefix(u8"    ");
+    }
+
+    void Manual::fill_opt_table() {
+        const auto &options = app.get_options();
+        for (const auto &reg_opt : options.all_options()) {
+            const auto &opt = reg_opt.get_option();
+        }
+    }
+
+    void Manual::fill_var_table() {}
+
+    void Manual::print_version(std::ostream &dst) const {
+        const auto &summary = this->app.get_summary();
+
+        dst << std::format
+        dst << summary.get_description() << std::endl;
+        dst << std::endl;
+    }
+
+    void Manual::print_help(std::ostream &dst) const {}
+
+#pragma endregion
+
+} // namespace yycc::carton::clap::manual::Manual
diff --git a/src/yycc/carton/clap/manual.hpp b/src/yycc/carton/clap/manual.hpp
new file mode 100644
index 0000000..8ce2751
--- /dev/null
+++ b/src/yycc/carton/clap/manual.hpp
@@ -0,0 +1,49 @@
+#pragma once
+#include "application.hpp"
+#include "../../macro/class_copy_move.hpp"
+#include "../tabulate.hpp"
+#include <iostream>
+
+#define NS_YYCC_CLAP ::yycc::carton::clap
+#define NS_YYCC_TABULATE ::yycc::carton::tabulate
+
+namespace yycc::carton::clap::manual::Manual {
+
+    struct ManualTr {
+    public:
+        ManualTr();
+        ~ManualTr();
+        YYCC_DEFAULT_COPY_MOVE(ManualTr);
+
+    public:
+        std::u8string author_and_version;
+        std::u8string usage_title, usage_body;
+        std::u8string avail_opt, avail_var;
+    };
+    
+    class Manual {
+    public:
+        Manual(const NS_YYCC_CLAP::application::Application& app, ManualTr&& trctx = ManualTr());
+        ~Manual();
+        YYCC_DEFAULT_COPY_MOVE(Manual);
+
+    private:
+        void setup_table();
+        void fill_opt_table();
+        void fill_var_table();
+
+    public:
+        void print_version(std::ostream& dst = std::cout) const;
+        void print_help(std::ostream& dst = std::cout) const;
+
+    private:
+        ManualTr trctx;
+        const NS_YYCC_CLAP::application::Application app;
+        NS_YYCC_TABULATE::Tabulate opt_printer;
+        NS_YYCC_TABULATE::Tabulate var_printer;
+    };
+
+}
+
+#undef NS_YYCC_TABULATE
+#undef NS_YYCC_CLAP
diff --git a/src/yycc/carton/clap/option.cpp b/src/yycc/carton/clap/option.cpp
index 8a72083..74f8df6 100644
--- a/src/yycc/carton/clap/option.cpp
+++ b/src/yycc/carton/clap/option.cpp
@@ -1,6 +1,6 @@
 #include "option.hpp"
 #include "../../string/op.hpp"
-#include "../../string/format.hpp"
+#include "../../patch/format.hpp"
 #include <stdexcept>
 #include <format>
 
diff --git a/src/yycc/carton/clap/variable.cpp b/src/yycc/carton/clap/variable.cpp
index 3a3ed1a..346f0b2 100644
--- a/src/yycc/carton/clap/variable.cpp
+++ b/src/yycc/carton/clap/variable.cpp
@@ -1,5 +1,5 @@
 #include "variable.hpp"
-#include "../../string/format.hpp"
+#include "../../patch/format.hpp"
 #include <stdexcept>
 #include <format>
 
diff --git a/src/yycc/carton/ironpad.cpp b/src/yycc/carton/ironpad.cpp
index c9403ec..70286bc 100644
--- a/src/yycc/carton/ironpad.cpp
+++ b/src/yycc/carton/ironpad.cpp
@@ -82,6 +82,8 @@ namespace yycc::carton::ironpad {
             m_UserCallback = callback;
             // mark registered
             m_IsRegistered = true;
+
+            return true;
         }
         /**
 		 * @brief Try to unregister unhandled exception handler.
diff --git a/src/yycc/string/format.hpp b/src/yycc/patch/format.hpp
similarity index 69%
rename from src/yycc/string/format.hpp
rename to src/yycc/patch/format.hpp
index b2bf73a..a2394d7 100644
--- a/src/yycc/string/format.hpp
+++ b/src/yycc/patch/format.hpp
@@ -8,15 +8,46 @@
  * By including this file directly, you will have abilities that use UTF8 string as argument in \c std::format with \c char char type.
 */
 #pragma once
-#include "reinterpret.hpp"
+#include "../string/reinterpret.hpp"
 #include <format>
 #include <string>
 #include <string_view>
 
 #define NS_YYCC_STRING_REINTERPRET ::yycc::string::reinterpret
 
+#pragma region Utf8 Format
+
+namespace yycc::patch::format {
+
+    // TODO: order all use of std::format redirect to this function.
+
+    template<class... Args>
+    std::string format(std::format_string<Args...> fmt, Args&&... args) {
+        return std::vformat(fmt.get(), std::make_format_args(args...));
+    }
+
+    template<class... Args>
+    std::u8string format(const std::u8string_view& fmt, Args&&... args) {
+        return NS_YYCC_STRING_REINTERPRET::as_utf8(
+            std::vformat(NS_YYCC_STRING_REINTERPRET::as_ordinary_view(fmt), std::make_format_args(args...)));
+    }
+
+} // namespace yycc::patch::format
+
+#pragma endregion
+
 #pragma region Utf8 Formatter
 
+// Add std::formatter specialization for "char8_t"
+template<>
+struct std::formatter<char8_t, char> {
+    constexpr auto parse(auto& ctx) { return underlying_formatter.parse(ctx); }
+    auto format(const char8_t& str, auto& ctx) const { return underlying_formatter.format(NS_YYCC_STRING_REINTERPRET::as_ordinary(str), ctx); }
+
+private:
+    std::formatter<char, char> underlying_formatter{};
+};
+
 // Add std::formatter specialization for "char8_t*"
 template<>
 struct std::formatter<char8_t*, char> {
@@ -43,7 +74,9 @@ private:
 template<std::size_t N>
 struct std::formatter<char8_t[N], char> {
     constexpr auto parse(auto& ctx) { return underlying_formatter.parse(ctx); }
-    auto format(const char8_t (&str)[N], auto& ctx) const { return underlying_formatter.format(std::basic_string_view<char>(str, N), ctx); }
+    auto format(const char8_t (&str)[N], auto& ctx) const {
+        return underlying_formatter.format(std::basic_string_view<char>(NS_YYCC_STRING_REINTERPRET::as_ordinary(str), N - 1), ctx);
+    }
 
 private:
     std::formatter<std::basic_string_view<char>, char> underlying_formatter{};
diff --git a/src/yycc/string/stream.cpp b/src/yycc/patch/stream.cpp
similarity index 88%
rename from src/yycc/string/stream.cpp
rename to src/yycc/patch/stream.cpp
index 1090842..34933fe 100644
--- a/src/yycc/string/stream.cpp
+++ b/src/yycc/patch/stream.cpp
@@ -1,9 +1,9 @@
 #include "stream.hpp"
-#include "reinterpret.hpp"
+#include "../string/reinterpret.hpp"
 
 #define REINTERPRET ::yycc::string::reinterpret
 
-namespace yycc::string::stream {
+namespace yycc::patch::stream {
 
     std::ostream& operator<<(std::ostream& os, const std::u8string_view& u8str) {
         os << REINTERPRET::as_ordinary_view(u8str);
diff --git a/src/yycc/string/stream.hpp b/src/yycc/patch/stream.hpp
similarity index 86%
rename from src/yycc/string/stream.hpp
rename to src/yycc/patch/stream.hpp
index 4a5b4df..4bcb281 100644
--- a/src/yycc/string/stream.hpp
+++ b/src/yycc/patch/stream.hpp
@@ -6,9 +6,9 @@
  * @brief This namespace add UTF8 support for \c std::ostream.
  * @details
  * The operator overloads written in this namespace will give \c std::ostream ability to write UTF8 string and its char.
- * For using this feature, please directly use <TT>using namespace yycc::string:stream;</TT> to import this namespace.
+ * For using this feature, please directly use <TT>using namespace yycc::patch:stream;</TT> to import this namespace.
  */
-namespace yycc::string::stream {
+namespace yycc::patch::stream {
 
     std::ostream& operator<<(std::ostream& os, const std::u8string_view& u8str);
     std::ostream& operator<<(std::ostream& os, const char8_t* u8str);
diff --git a/src/yycc/string/reinterpret.cpp b/src/yycc/string/reinterpret.cpp
index 8f9e859..e12abc5 100644
--- a/src/yycc/string/reinterpret.cpp
+++ b/src/yycc/string/reinterpret.cpp
@@ -2,6 +2,9 @@
 
 namespace yycc::string::reinterpret {
 
+    char8_t as_utf8(const char& src) {
+        return static_cast<char8_t>(src);
+    }
     const char8_t* as_utf8(const char* src) {
         return reinterpret_cast<const char8_t*>(src);
     }
@@ -15,6 +18,9 @@ namespace yycc::string::reinterpret {
         return std::u8string_view(reinterpret_cast<const char8_t*>(src.data()), src.size());
     }
 
+    char as_ordinary(char8_t src) {
+        return static_cast<char>(src);
+    }
     const char* as_ordinary(const char8_t* src) {
         return reinterpret_cast<const char*>(src);
     }
diff --git a/src/yycc/string/reinterpret.hpp b/src/yycc/string/reinterpret.hpp
index f5acb1e..67e86c6 100644
--- a/src/yycc/string/reinterpret.hpp
+++ b/src/yycc/string/reinterpret.hpp
@@ -11,52 +11,64 @@
  */
 namespace yycc::string::reinterpret {
 
+    /**
+     * @brief Reinterpret ordinary char type to UTF-8 char type.
+     * @param[in] src Source ordinary char value.
+     * @return UTF8 char value.
+     */
+    char8_t as_utf8(const char& src);
 	/**
 	 * @brief Reinterpret ordinary C-string to UTF-8 string (const version).
-	 * @param src Source ordinary string
+	 * @param[in] src Source ordinary string
 	 * @return Pointer to UTF-8 encoded string
 	 */
     const char8_t* as_utf8(const char* src);
 	/**
 	 * @brief Reinterpret ordinary C-string as an UTF-8 string (non-const version).
-	 * @param src Source ordinary string
+	 * @param[in] src Source ordinary string
 	 * @return Pointer to UTF-8 encoded string
 	 */
     char8_t* as_utf8(char* src);
 	/**
 	 * @brief Reinterpret ordinary string view to copied UTF-8 string.
-	 * @param src Source ordinary string view
+	 * @param[in] src Source ordinary string view
 	 * @return UTF-8 encoded string
 	 */
     std::u8string as_utf8(const std::string_view& src);
 	/**
 	 * @brief Reinterpret ordinary string view to UTF-8 string view.
-	 * @param src Source ordinary string view
+	 * @param[in] src Source ordinary string view
 	 * @return UTF-8 encoded string view
 	 */
     std::u8string_view as_utf8_view(const std::string_view& src);
 
+    /**
+     * @brief Reinterpret UTF-8 char type to ordinary char type.
+     * @param[in] src Source UTF-8 char value.
+     * @return Ordinary char value.
+     */
+    char as_ordinary(char8_t src);
 	/**
 	 * @brief Reinterpret UTF-8 C-string to ordinary string (const version).
-	 * @param src Source UTF-8 string
+	 * @param[in] src Source UTF-8 string
 	 * @return Pointer to ordinary string
 	 */
     const char* as_ordinary(const char8_t* src);
 	/**
 	 * @brief Reinterpret UTF-8 C-string to ordinary string (non-const version).
-	 * @param src Source UTF-8 string
+	 * @param[in] src Source UTF-8 string
 	 * @return Pointer to ordinary string
 	 */
     char* as_ordinary(char8_t* src);
 	/**
 	 * @brief Reinterpret UTF-8 string view to ordinary string.
-	 * @param src Source UTF-8 string view
+	 * @param[in] src Source UTF-8 string view
 	 * @return Ordinary string
 	 */
     std::string as_ordinary(const std::u8string_view& src);
 	/**
 	 * @brief Reinterpret UTF-8 string view to ordinary string view
-	 * @param src Source UTF-8 string view
+	 * @param[in] src Source UTF-8 string view
 	 * @return Ordinary string view
 	 */
     std::string_view as_ordinary_view(const std::u8string_view& src);
diff --git a/testbench/CMakeLists.txt b/testbench/CMakeLists.txt
index 167b75e..6da20b3 100644
--- a/testbench/CMakeLists.txt
+++ b/testbench/CMakeLists.txt
@@ -18,10 +18,11 @@ PRIVATE
     yycc/constraint/builder.cpp
     yycc/patch/ptr_pad.cpp
     yycc/patch/fopen.cpp
+    yycc/patch/stream.cpp
+    yycc/patch/format.cpp
     yycc/rust/env.cpp
     yycc/string/reinterpret.cpp
     yycc/string/op.cpp
-    yycc/string/stream.cpp
     yycc/num/parse.cpp
     yycc/num/stringify.cpp
     yycc/num/op.cpp
diff --git a/testbench/yycc/patch/format.cpp b/testbench/yycc/patch/format.cpp
new file mode 100644
index 0000000..b33b667
--- /dev/null
+++ b/testbench/yycc/patch/format.cpp
@@ -0,0 +1,35 @@
+#include <gtest/gtest.h>
+#include <yycc.hpp>
+#include <yycc/patch/format.hpp>
+
+#define FORMAT ::yycc::patch::format
+
+namespace yycctest::patch::format {
+
+    static constexpr char8_t PROBE[] = u8"hello";
+    static std::u8string PROBE_STRING(PROBE);
+    static constexpr std::u8string_view PROBE_STRING_VIEW(PROBE);
+
+    TEST(PatchFormat, OrdinaryFormat) {
+        auto rv = FORMAT::format("{}{}{}{}{}{} world!",
+                                 PROBE[0],
+                                 PROBE_STRING.data(),
+                                 PROBE_STRING.c_str(),
+                                 PROBE,
+                                 PROBE_STRING,
+                                 PROBE_STRING_VIEW);
+        EXPECT_EQ(rv, "104hellohellohellohellohello world!");
+    }
+
+    TEST(PatchFormat, Utf8Format) {
+        auto rv = FORMAT::format(u8"{}{}{}{}{}{} world!",
+                                 PROBE[0],
+                                 PROBE_STRING.data(),
+                                 PROBE_STRING.c_str(),
+                                 PROBE,
+                                 PROBE_STRING,
+                                 PROBE_STRING_VIEW);
+        EXPECT_EQ(rv, u8"104hellohellohellohellohello world!");
+    }
+
+}
diff --git a/testbench/yycc/string/stream.cpp b/testbench/yycc/patch/stream.cpp
similarity index 73%
rename from testbench/yycc/string/stream.cpp
rename to testbench/yycc/patch/stream.cpp
index 001264a..69a75e7 100644
--- a/testbench/yycc/string/stream.cpp
+++ b/testbench/yycc/patch/stream.cpp
@@ -1,28 +1,28 @@
 #include <gtest/gtest.h>
 #include <yycc.hpp>
-#include <yycc/string/stream.hpp>
+#include <yycc/patch/stream.hpp>
 #include <yycc/string/reinterpret.hpp>
 #include <sstream>
 
 #define REINTERPRET ::yycc::string::reinterpret
 using namespace std::literals::string_view_literals;
-using namespace ::yycc::string::stream;
+using namespace ::yycc::patch::stream;
 
-namespace yycctest::string::stream {
+namespace yycctest::patch::stream {
     
-    TEST(StringStream, StringView) {
+    TEST(PatchStream, StringView) {
         std::stringstream ss;
         ss << u8"hello"sv;
         EXPECT_EQ(REINTERPRET::as_utf8_view(ss.view()), u8"hello"sv);
     }
 
-    TEST(StringStream, CStrPtr) {
+    TEST(PatchStream, CStrPtr) {
         std::stringstream ss;
         ss << u8"hello";
         EXPECT_EQ(REINTERPRET::as_utf8_view(ss.view()), u8"hello");
     }
 
-    TEST(StringStream, Character) {
+    TEST(PatchStream, Character) {
         std::stringstream ss;
         ss << u8'y';
         EXPECT_EQ(REINTERPRET::as_utf8_view(ss.view()), u8"y");
diff --git a/testbench/yycc/string/reinterpret.cpp b/testbench/yycc/string/reinterpret.cpp
index 4297fae..0dbe128 100644
--- a/testbench/yycc/string/reinterpret.cpp
+++ b/testbench/yycc/string/reinterpret.cpp
@@ -6,6 +6,7 @@
 #include <yycc/rust/prelude.hpp>
 
 #define REINTERPRET ::yycc::string::reinterpret
+#define AS_UINT8(p) static_cast<u8>(p)
 #define CONST_VOID_PTR(p) reinterpret_cast<const void*>(p)
 #define VOID_PTR(p) reinterpret_cast<void*>(p)
 
@@ -13,6 +14,16 @@ namespace yycctest::string::reinterpret {
 
     static std::u8string PROBE(u8"Test");
 
+    TEST(StringReinterpret, Character) {
+        const auto& src = PROBE[0];
+        const auto dst = REINTERPRET::as_ordinary(src);
+        const auto new_src = REINTERPRET::as_utf8(dst);
+
+        // Value should be the same after casting.
+        EXPECT_EQ(AS_UINT8(src), AS_UINT8(dst));
+        EXPECT_EQ(AS_UINT8(src), AS_UINT8(new_src));
+    }
+
     TEST(StringReinterpret, ConstPointer) {
         const auto* src = PROBE.data();
         const auto* dst = REINTERPRET::as_ordinary(src);
@@ -33,7 +44,7 @@ namespace yycctest::string::reinterpret {
         EXPECT_EQ(VOID_PTR(src), VOID_PTR(new_src));
     }
 
-    TEST(StringReinterpret, String) {
+    TEST(StringReinterpret, StlString) {
         auto src = std::u8string(PROBE);
         auto dst = REINTERPRET::as_ordinary(src);
         auto new_src = REINTERPRET::as_utf8(dst);
@@ -45,7 +56,7 @@ namespace yycctest::string::reinterpret {
         EXPECT_TRUE(std::memcmp(src.data(), new_src.data(), src.length()) == 0);
     }
 
-    TEST(StringReinterpret, StringView) {
+    TEST(StringReinterpret, StlStringView) {
         auto src = std::u8string_view(PROBE);
         auto dst = REINTERPRET::as_ordinary_view(src);
         auto new_src = REINTERPRET::as_utf8_view(dst);