Mrs. Yamada is the mother of Seina and Yoshiko, and helped Seina's father to run the small grocery store the Yamadas owned. She was also the one most enthusiastic about the possibility of a prize when Amane gave Seina a Galaxy Police application, and helped fill it out. She also kept an album of Seina growing up, with mostly pictures of Seina's various injuries from his bad luck.
In the Light Novels, her name is given as Kyoko.
- JAPANESE - Keiko Onodera (小野寺 啓子)
- ENGLISH - Julie Maddalena