Puberty syndrome – Abnormal experiences rumored on the internet to be caused by sensitivity and instability during adolescence. This year, Sakuta Azusagawa, a second-year student at a high school near Enoshima, meets several girls that are experiencing this “puberty syndrome.” For instance, he meets a wild bunny girl in the library. She turns out to be an actress on hiatus, Mai Sakurajima, who is also his senior at the school. For some reason, no one else can see this enchanting girl. How did she become invisible…? As Sakuta searches for answers to help Mai, they spend more time together, and he eventually learns of her hidden feelings… This is an unusual story that takes place in a town of bright skies and glistening seas, where Sakuta encounters various intriguing girls.

Soon after Mai's "puberty syndrome" is resolved, Sakuta encounters another strange phenomenon without respite. Day after day, it is the same day for Sakuta and there is no tomorrow. When he consults Rio, she raises the possibility of "Laplace’s demon" -- that someone may be repeating and redoing a day.

It is now the last day of the first term, the promised day when pretending to be dating Tomoe ends. It seems as though everything has finally been resolved, but…