Toshi Ryoko's mother. She left town 6 years ago, as mysteriously as her mother before her, due to the Ryoko Family Curse. Toshi has found evidence that she is compelled to look for something.
Kyoko left her family when Haruki was 7 years old.
Riho has no idea where Haruki went and feels hurt and betrayed by her sudden disappearance. She also feels somewhat responsible for indulging her obsessive research before she left.