diff --git a/src/mir/builder/calls/lowering.rs b/src/mir/builder/calls/lowering.rs
index 12cd7a64..47988373 100644
--- a/src/mir/builder/calls/lowering.rs
+++ b/src/mir/builder/calls/lowering.rs
@@ -268,21 +268,42 @@ impl MirBuilder {
         let mut slot_regs: Vec<(String, Option<MirType>)> = Vec::new();
 
         if let Some(ref mut f) = self.current_function {
-            // 📦 Hotfix 6: Use pre-reserved ValueIds instead of generating new ones
-            // MirFunction::new() already reserved ValueIds 0..N for parameters
-            // First parameter is always 'me' at ValueId(0)
-            let me_id = ValueId(0);
-            f.params.push(me_id);
+            // 📦 Hotfix 6 改訂版:
+            // MirFunction::new() が既に 0..N の ValueId を params 用に予約しているので、
+            // ここではそれを「上書き使用」するだけにして、push で二重定義しないようにするよ。
+            //
+            // params レイアウト:
+            //   index 0: me (box<MyBox>)
+            //   index 1..: 通常パラメータ
+            if f.params.is_empty() {
+                // 安全弁: 何らかの理由で pre-populate されていない場合は従来どおり new する
+                let me_id = ValueId(0);
+                f.params.push(me_id);
+                for i in 0..params.len() {
+                    f.params.push(ValueId((i + 1) as u32));
+                }
+            }
+
+            // me
+            let me_id = f.params[0];
             self.variable_map.insert("me".to_string(), me_id);
             self.value_origin_newbox.insert(me_id, box_name.to_string());
             slot_regs.push(("me".to_string(), None));
 
-            // Then regular parameters at ValueId(1), ValueId(2), ...
+            // 通常パラメータ
             for (idx, p) in params.iter().enumerate() {
-                let pid = ValueId((idx + 1) as u32);
-                f.params.push(pid);
-                self.variable_map.insert(p.clone(), pid);
-                slot_regs.push((p.clone(), None));
+                let param_idx = idx + 1;
+                if param_idx < f.params.len() {
+                    let pid = f.params[param_idx];
+                    self.variable_map.insert(p.clone(), pid);
+                    slot_regs.push((p.clone(), None));
+                } else {
+                    // 念のため足りない場合は新規に確保（互換用）
+                    let pid = f.next_value_id();
+                    f.params.push(pid);
+                    self.variable_map.insert(p.clone(), pid);
+                    slot_regs.push((p.clone(), None));
+                }
             }
         }
 
diff --git a/src/mir/builder/calls/unified_emitter.rs b/src/mir/builder/calls/unified_emitter.rs
index 62368705..dd216961 100644
--- a/src/mir/builder/calls/unified_emitter.rs
+++ b/src/mir/builder/calls/unified_emitter.rs
@@ -177,6 +177,14 @@ impl UnifiedCallEmitterBox {
         let mut args_local: Vec<ValueId> = args;
         crate::mir::builder::emit_guard::finalize_call_operands(builder, &mut callee, &mut args_local);
 
+        // 📦 Hotfix 7: Include receiver in args for Callee::Method
+        // VM's exec_function_inner expects receiver as the first parameter (ValueId(0))
+        // but finalize_call_operands keeps receiver in Callee, not in args.
+        // We must add it to args_local here so VM can bind it correctly.
+        if let Callee::Method { receiver: Some(recv), .. } = &callee {
+            args_local.insert(0, *recv);
+        }
+
         // Create MirCall instruction using the new module (pure data composition)
         let mir_call = call_unified::create_mir_call(dst, callee.clone(), args_local.clone());