Summer has come again this year──. While munching on a watermelon, Natsu and her only son Kenji laughed as they recalled the hellish heat of last summer when their air conditioner broke. One day, Natsu and Kenji finally reached for the remote control of the air conditioner for the first time this year… However, no matter how many times they pressed the remote, the air conditioner showed no response. "Mom, the air conditioner is broken again this year." Following last year's events, Natsu and Kenji's sweaty summer vacation began once more.
