Yoriko Yasaka is Mahiro Yasaka's mother and a monster hunter, a profession she started in college. She kept this secret from Mahiro until a major plot event brought her home. Despite having a high school-aged son, her strikingly youthful look frequently surprises others.

She wields ordinary dining forks as throwing weapons with exceptional skill and carries far more than Mahiro. Kind and optimistic, especially towards non-hostile aliens, she allowed Nyaruko, Kuuko, and Hasuta to live in her home partly out of gratitude after they aided her rescue during a crisis.

A dedicated gaming enthusiast, she often buys new consoles after missions and bonds over this hobby with Kuuko. She showers Mahiro with affection, hugging him to recharge her self-described "son-onium," sometimes embarrassing him. Initially advising Nyaruko to temper her pursuit of Mahiro, she later approved their relationship following her rescue. Her combat expertise extends beyond forks to conventional weapons like shotguns and rocket launchers. She sometimes adopts the pose and catchphrase of Cure Moonlight from *Fresh Pretty Cure!*.