A Miniskirt Santa suddenly appears before Sakuta. She says her name is "Touko Kirishima" and claims to have been handing out Puberty Syndrome to people as gifts. Sakuta sees her eyes lock on Ikumi Akagi, a former middle school classmate who is attending the same university as Sakuta, studying in the nursing program. Curious about Ikumi, Sakuta goes on a group date with female nursing program students that his friend invited him to. There, they discuss a rumor about people's dreams coming true after they post about them on social media with the hashtag #DREAMING...

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