Shirakawa works as the head of the PE department and advisor of the gymnastic club. She is described best as a tsundere: blunt and serious almost stoic sometimes and when around Takeshi, become more willing (usually when horny). She tends to ask Takeshi to help her with equipment and exercise and when he was sick pretended to be his wife when she took care of him. Shirakawa sometimes thinks oddly like thinking that if a bride puts a few strawberries on a wedding cake then it becomes homemade.
When she first Takeshi, it was when he helped her with the gymnastics club. When she noticed leotards turn him on she tried having sex with him in a leotard to let him get over his fetish but it only reinforced it. Often the two are together working on physical exercise activity. Sometimes after having sex with Takeshi Kono, she becomes turned on by the objected involved in their sex act like rope or bloomers. She even kept a bikini she had sex in with him. There are hints that she wishes to be his wife.