diff --git a/docs/private b/docs/private
index 63f53bbd..a5d43baa 160000
--- a/docs/private
+++ b/docs/private
@@ -1 +1 @@
-Subproject commit 63f53bbde9220ecb8f9830ebb5f5761fa0348624
+Subproject commit a5d43baaaf5f7b40c240c29a44756689b5dc7c2f
diff --git a/lang/src/compiler/emit/common/call_emit_box.hako b/lang/src/compiler/emit/common/call_emit_box.hako
index 0a15d049..a32bb150 100644
--- a/lang/src/compiler/emit/common/call_emit_box.hako
+++ b/lang/src/compiler/emit/common/call_emit_box.hako
@@ -41,6 +41,19 @@ static box CallEmitBox {
     return {op: "mir_call", dst: dst, callee: callee, args: arg_ids}
   }
 
+  make_mir_call_closure(params, captures, me_capture, dst) {
+    local callee = {type: "Closure", params: params, captures: captures}
+    if me_capture != null {
+      callee.me_capture = me_capture
+    }
+    return {op: "mir_call", dst: dst, callee: callee, args: []}
+  }
+
+  make_mir_call_value(func_vid, arg_ids, dst) {
+    local callee = {type: "Value", value: func_vid}
+    return {op: "mir_call", dst: dst, callee: callee, args: arg_ids}
+  }
+
   _canonical_module_name(name, arity) {
     if name == null { return "" }
     if name.indexOf("/") >= 0 { return name }
diff --git a/lang/src/llvm_ir/instructions/mir_call.hako b/lang/src/llvm_ir/instructions/mir_call.hako
index 80de76e9..d9df4657 100644
--- a/lang/src/llvm_ir/instructions/mir_call.hako
+++ b/lang/src/llvm_ir/instructions/mir_call.hako
@@ -114,71 +114,33 @@ static box LLVMMirCallInstructionBox {
   }
 
   // Stage 4: Closure creation
-  // TODO: CallEmitBox に make_mir_call_closure を追加する必要あり
+  // CallEmitBox.make_mir_call_closure を活用
   _lower_closure(self, callee, args, dst) {
-    // Placeholder: 将来実装
     local params = callee.get("params")
     local captures = callee.get("captures")
+    local me_capture = callee.get("me_capture")
 
-    local json = "{"
-    json = json + "\"op\":\"mir_call\""
-    json = json + ",\"dst\":" + dst.toString()
-    json = json + ",\"callee\":{\"type\":\"Closure\""
-
-    // params 配列
-    if params != null {
-      json = json + ",\"params\":" + me._array_to_json(self, params)
+    if params == null {
+      params = new ArrayBox()
+    }
+    if captures == null {
+      captures = new ArrayBox()
     }
 
-    // captures 配列
-    if captures != null {
-      json = json + ",\"captures\":" + me._array_to_json(self, captures)
-    }
-
-    json = json + "}"
-    json = json + ",\"args\":" + me._array_to_json(self, args)
-    json = json + "}"
-
-    return json
+    local json_obj = CallEmitBox.make_mir_call_closure(params, captures, me_capture, dst)
+    return JsonEmitBox.to_json_instruction(json_obj)
   }
 
   // Stage 4: Value call (dynamic function value)
-  // TODO: CallEmitBox に make_mir_call_value を追加する必要あり
+  // CallEmitBox.make_mir_call_value を活用
   _lower_value(self, callee, args, dst) {
-    // Placeholder: 将来実装
     local func_vid = callee.get("value")
     if func_vid == null {
       return me._mir_call_error_fallback(self, "Value: value is null")
     }
 
-    local json = "{"
-    json = json + "\"op\":\"mir_call\""
-    json = json + ",\"dst\":" + dst.toString()
-    json = json + ",\"callee\":{\"type\":\"Value\",\"value\":" + func_vid.toString() + "}"
-    json = json + ",\"args\":" + me._array_to_json(self, args)
-    json = json + "}"
-
-    return json
-  }
-
-  // Helper: ArrayBox を JSON 配列に変換
-  _array_to_json(self, arr) {
-    if arr == null {
-      return "[]"
-    }
-    local json = "["
-    local size = arr.size()
-    local i = 0
-    loop(i < size) {
-      if i > 0 {
-        json = json + ","
-      }
-      local val = arr.get(i)
-      json = json + val.toString()
-      i = i + 1
-    }
-    json = json + "]"
-    return json
+    local json_obj = CallEmitBox.make_mir_call_value(func_vid, args, dst)
+    return JsonEmitBox.to_json_instruction(json_obj)
   }
 
   // エラーフォールバック: 空の MIR Call を返す
diff --git a/tests/phase33/smoke/mir_call/closure_simple.hako b/tests/phase33/smoke/mir_call/closure_simple.hako
new file mode 100644
index 00000000..4cb33b66
--- /dev/null
+++ b/tests/phase33/smoke/mir_call/closure_simple.hako
@@ -0,0 +1,58 @@
+// MIR Call Smoke Test 2: Closure creation
+// Tests Closure callee type
+
+using "lang/src/llvm_ir/instructions/mir_call.hako" as MirCallInst
+
+static box Main {
+  main() {
+    print("=== MIR Call Smoke Test 2: closure_simple ===")
+
+    // Simulate: |x, y| { x + y }
+    local callee = new MapBox()
+    callee.set("type", "Closure")
+
+    local params = new ArrayBox()
+    params.push(1)  // param x
+    params.push(2)  // param y
+    callee.set("params", params)
+
+    local captures = new ArrayBox()
+    captures.push(3)  // captured variable
+    callee.set("captures", captures)
+
+    local args = new ArrayBox()
+
+    // Generate mir_call JSON
+    local json = MirCallInst.lower_mir_call(null, callee, args, 4, null)
+
+    // Verify JSON structure
+    local has_mir_call = json.indexOf("\"op\":\"mir_call\"")
+    if has_mir_call < 0 {
+      print("ERROR: op not found")
+      return 1
+    }
+
+    local has_closure = json.indexOf("\"type\":\"Closure\"")
+    if has_closure < 0 {
+      print("ERROR: Closure type not found")
+      return 1
+    }
+
+    local has_params = json.indexOf("\"params\"")
+    if has_params < 0 {
+      print("ERROR: params not found")
+      return 1
+    }
+
+    local has_captures = json.indexOf("\"captures\"")
+    if has_captures < 0 {
+      print("ERROR: captures not found")
+      return 1
+    }
+
+    print("✓ PASS: closure_simple mir_call generated")
+    print("Note: Actual execution requires C++ backend implementation")
+
+    return 0
+  }
+}
diff --git a/tests/phase33/smoke/mir_call/value_simple.hako b/tests/phase33/smoke/mir_call/value_simple.hako
new file mode 100644
index 00000000..bfd709ff
--- /dev/null
+++ b/tests/phase33/smoke/mir_call/value_simple.hako
@@ -0,0 +1,46 @@
+// MIR Call Smoke Test 3: Value call (dynamic function)
+// Tests Value callee type
+
+using "lang/src/llvm_ir/instructions/mir_call.hako" as MirCallInst
+
+static box Main {
+  main() {
+    print("=== MIR Call Smoke Test 3: value_simple ===")
+
+    // Simulate: func_value(arg1, arg2)
+    local callee = new MapBox()
+    callee.set("type", "Value")
+    callee.set("value", 5)  // register holding function value
+
+    local args = new ArrayBox()
+    args.push(6)  // arg1
+    args.push(7)  // arg2
+
+    // Generate mir_call JSON
+    local json = MirCallInst.lower_mir_call(null, callee, args, 8, null)
+
+    // Verify JSON structure
+    local has_mir_call = json.indexOf("\"op\":\"mir_call\"")
+    if has_mir_call < 0 {
+      print("ERROR: op not found")
+      return 1
+    }
+
+    local has_value = json.indexOf("\"type\":\"Value\"")
+    if has_value < 0 {
+      print("ERROR: Value type not found")
+      return 1
+    }
+
+    local has_value_id = json.indexOf("\"value\":5")
+    if has_value_id < 0 {
+      print("ERROR: value ID not found")
+      return 1
+    }
+
+    print("✓ PASS: value_simple mir_call generated")
+    print("Note: Actual execution requires C++ backend implementation")
+
+    return 0
+  }
+}