Kenji was left alone after his wife returned home to give birth, and his sister-in-law, Mai, was so worried that she came to check on him. Kenji, who liked Mai's lovely smile, happily accepted Mai and was very happy to see her again after such a long time. However, Mai's real purpose is to take out her frustrations on Kenji, as her marital relationship is not going well. Mai sneaks up on Kenji, who is carefreely taking a bath without realizing it.
