With her dad overseas during Christmas, Miku tries to get her friends to dress as Santa to make Ryuuta believe he exists. Noticing Hitoha's habit of hiding under Yabe's desk, Miyashita tries to utilise that so she can become friends with her. Later, class 6-1 teacher Kaieda fills in for Yabe's class and comes into trouble whilst dealing with Futaba, who is using written notes as she has lost her voice. Oh a hot day, Mitsuba goes to great lengths to get the air conditioner working, only to foiled by her sweat and weight. With the class assigned to pool cleanup, the boys and girls have a human curling contest to see who has to clean up.