diff --git a/ctr/Makefile b/ctr/Makefile
new file mode 100644
index 0000000..d9836e8
--- /dev/null
+++ b/ctr/Makefile
@@ -0,0 +1,2 @@
+all:
+	g++ -std=c++14 -o sample sample.cpp
diff --git a/ctr/sample.cpp b/ctr/sample.cpp
new file mode 100644
index 0000000..a36c22a
--- /dev/null
+++ b/ctr/sample.cpp
@@ -0,0 +1,201 @@
+// ctrd - A framework for Contract Description
+//
+// HOW TO USE
+//
+// ```
+// using ...::me;
+//
+// UNLESS(cond).FIX(me);
+// ```
+//
+// ```
+// UNLESS(cond).FIX(caller);
+// ```
+//
+// (TO BE ADDED)
+//
+// UNLESS(cond).FIX("..."); // FIX SUBCOMPONENT
+#include <memory>
+
+#include <cassert>
+#include <iostream>
+
+//
+// FRAMEWORK CODE
+//
+namespace ctr
+{
+
+class Handler;
+
+struct Frame // Nested Frame
+{
+private:
+  std::shared_ptr<Frame> const _parent;
+  const Handler * const _handler = nullptr;
+
+public:
+  Frame(const std::shared_ptr<Frame> &p, const Handler *h) : _parent{p}, _handler{h}
+  {
+    // DO NOTHING
+  }
+
+public:
+  const std::shared_ptr<Frame> &parent(void) const { return _parent; }
+  const Handler *handler(void) const { return _handler; }
+};
+
+struct ThreadContext // Thread-local Context
+{
+public:
+  friend class Tracker;
+  friend class Handler;
+
+private: // Only Tracker and Handler are allowed to access this field
+  std::shared_ptr<Frame> top;
+
+private:
+  static ThreadContext &get(void)
+  {
+    thread_local ThreadContext ctx;
+    return ctx;
+  }
+};
+
+class Handler
+{
+public:
+  struct FaultByMe final
+  {
+  };
+
+  struct FaultByCaller final
+  {
+  };
+
+private:
+  std::shared_ptr<Frame> _frame;
+
+public:
+  Handler()
+  {
+    _frame = std::make_shared<Frame>(ThreadContext::get().top, this);
+    ThreadContext::get().top = _frame;
+  }
+
+public:
+  virtual ~Handler()
+  {
+    assert(ThreadContext::get().top == _frame);
+    ThreadContext::get().top = _frame->parent();
+  }
+
+public:
+  enum class PostAction
+  {
+    Stop,
+    Go,
+  };
+
+  virtual PostAction handle(const FaultByMe &) const { return PostAction::Go; }
+  virtual PostAction handle(const FaultByCaller &) const { return PostAction::Go; }
+};
+
+struct Me // Phantom Type
+{
+};
+
+Me me;
+
+struct Caller // Phantom Type
+{
+};
+
+Caller caller;
+
+class Tracker // TODO Keep __FILE__ and __LINE__
+{
+private:
+  template <typename Callable> void visit_frame_with_(Callable &&f) const
+  {
+    auto frame = ThreadContext::get().top;
+
+    for (auto frame = ThreadContext::get().top; frame != nullptr; frame = frame->parent())
+    {
+      switch (f(frame->handler()))
+      {
+      case Handler::PostAction::Stop:
+        return;
+      case Handler::PostAction::Go:
+      default:
+        break;
+      }
+    }
+
+    assert(false);
+  }
+
+public:
+  void FIX(const Me &) const
+  {
+    Handler::FaultByMe fault;
+    visit_frame_with_([&fault] (const Handler *h) { return h->handle(fault); });
+  }
+
+  void FIX(const Caller &) const
+  {
+    Handler::FaultByCaller fault;
+    visit_frame_with_([&fault] (const Handler *h) { return h->handle(fault); });
+  }
+};
+
+Tracker make_tracker(void) { return Tracker{}; }
+
+} // namespace ctr
+
+#define UNLESS(cond) if (not (cond)) ::ctr::make_tracker()
+
+//
+// USER CODE
+//
+using ctr::me;
+using ctr::caller;
+
+struct MyHandler final : public ctr::Handler
+{
+  // Override this method to handle "my fault"
+  PostAction handle(const FaultByMe &) const final
+  {
+    std::cerr << "My Fault" << std::endl;
+    return PostAction::Stop;
+  }
+
+  PostAction handle(const FaultByCaller &) const final
+  {
+    std::cerr << "Caller's Fault" << std::endl;
+    throw std::runtime_error{"caller's fault!"};
+  }
+};
+
+int main(int argc, char **argv)
+{
+  int x = 4;
+
+  {
+    MyHandler h;
+
+    std::cout << __LINE__ << std::endl;
+    UNLESS(x == 3).FIX(me);
+    std::cout << __LINE__ << std::endl;
+
+    std::cout << __LINE__ << std::endl;
+    UNLESS(x == 3).FIX(caller);
+    std::cout << __LINE__ << std::endl;
+  }
+
+  std::cout << __LINE__ << std::endl;
+  UNLESS(x == 3).FIX(caller);
+  std::cout << __LINE__ << std::endl;
+
+  return 0;
+}