Todou, Erika

Yuuto's step-sister, who secretly harbors a crush on him. She reveals this through jealousy and by teasing Yuuto about his "oedipal" attraction to his step-mother. Their relationship shifts following an argument where Yuuto complains that Erika is too focused on her studies and lacks skill in household chores. She subsequently offers to assist him in a different manner by providing sexual favors, which he readily accepts. They try to keep their relationship hidden, but others notice the change in the siblings. One of them is Yuhi, a fellow female classmate who is romantically interested in Erika.