Yuma Okazaki and Hotaru Mizushina, both high school students, were childhood friends. Their lives couldn't be more perfect with their respective partners, Takeda and Fujiwara. Nothing appears to be able to sever their friendship, from playing in school to going on group outings. During one of these group dates, though, Hotaru makes an unexpected move. She starts massaging Yuma's thighs while Takeda and Fujiwara are busy. Yuma, taken aback by this unusual gesture, flees uncomfortably to the restroom, followed quickly by her assailant. Hotaru now drags Yuma into a closed cubicle and whispers into her ear, "You'll be more frightened with a male; I'll help you practice."