Mika is a woman of average height with medium-length hair and wears a sweater dress.
After her boyfriend Yoma Hashimoto becomes obsessed with fitness, Mika trips on the weights he leaves lying on the ground of her apartment floor and cries for him to put them away. She points out that Yoma has been gaining definition in his muscles lately and is impressed that someone could transform so quickly. Despite cooking walleye pollock roe spaghetti for the two of them for dinner, Yoma refuses to eat it because he's avoiding carbs. Mika becomes frustrated with Yoma canceling plans they made together and has to apologize to a deliveryman for Yoma threatening to murder him.
Later, she finds Yoma bouldering within her small apartment room and thinks he's insane. She demands to get back 270,000 yen Yoma stole from her credit card and threatens to call the police if he doesn't leave.