Yayoi Ogawa runs the boarding house where residents Hiroe Ogawa and Mayaka live. Hiroe nicknames her "Mom," a term later clarified in translations to signify her role solely as landlady. Yayoi maintains a collection of S&M equipment and sexual toys in her closet.

During the second episode, she interrupts a sexual contest between Mayaka and Takami and joins the activity. Later, she employs rapid-fire anal sex while wearing a leather suit to subdue Takami's friends when they intrude on the boarding house. In the third episode, when Hiroe is possessed by an incubus, Yayoi aids the exorcism by electrocuting Hiroe with a super-charged vibrator. Her actions consistently involve facilitating or directly participating in sexual scenarios to resolve situations concerning the residents.