Mr and Mrs. Yamada
The parents of Seina. They ran a small grocery at the start of the series. Due to their son's terrible luck, he often causes himself injury and damage to their home and shop. For this reason, they are happy to their son to The Gaalxy Police when the opportunity rises, by stealing the reluctant boy's signature and thumbprint. Their decision eventually pays off; the interest from Seina's excessive salary was forwarded to them, allowing them to build a huge new home and a supermarket. They are present when Seto announces Seina's marriage to the girls, and both try to convince him to go along with it.
The younger sister of Seina. She teased Seina about his bad luck and supported her parents' decision to send him away. She was present at the announcement of Seina's engagement and was excited at the idea of having four older sisters. At this time, she also becomes engaged to Kai Masaki. She was present when The Renzan girls kidnapped him, but did nothing to stop them.