public void ManagedUpdate()
    {
        switch (state)
        {
        case STATE.KEY:
            key.ManagedUpdate();
            break;

        case STATE.NOISY:
            noisy.ManagedUpdate();
            break;

        case STATE.GARBAGE:
            garbage.ManagedUpdate();
            break;

        default:
            Debug.Log("何かがおかしいよ! at Item ManagedUpdate()");
            break;
        }
    }