S2, E6: A poltergeist-like phenomenon attacks Ikumi. Sakuta is worried the attack was caused by Puberty Syndrome, but Ikumi claims that the only way to fix this problem is by forgetting about Sakuta’s existence. Hearing this, Sakuta is stunned and confused. Without giving him the time to compose his thoughts, Ikumi proposes that they have a contest, competing to see if Sakuta will remember “that day” first, or if Ikumi will forget about Sakuta first.