Youngster Otsuka, who has started working at a convenience store, has one thing to worry about. It's about Mr. Muto, a senior part-time worker with an eerie atmosphere...?

Mr. Oda, a regular customer at a convenience store, notices an unusual matter. The handmade rice balls are tastier than before. It seems that Mr. Muto, a part-time worker, is involved this matter...?