"Forget what you saw today." There's something odd about Sakuta Azusagawa, an acerbic, standoffish high schooler who doesn't even own a cell phone in this day and age. And perhaps strange things happen to strange people, which is why on the last day of the Golden Week holiday, in a tranquil library, he meets a wild bunny girl. With that unforgettable encounter, their bizarre and mysterious love story begins.

“Today...is yesterday?” Sakuta may have cured Mai’s Adolescence Syndrome in the nick of time, but now he faces a no-less-harrowing task: convincing her to officially date him. After managing to win that round of verbal fencing, he gets some well-deserved rest...only to wake up “yesterday,” with all his progress reset. This inexplicable phenomenon seems to be caused by Tomoe Koga—the self-righteous yet self-conscious schoolgirl who offered up her own butt to be kicked after mistakenly assaulting Sakuta’s—and the only cure is to...pretend to be her boyfriend?!

Sakuta Azusagawa meets a bunny girl in the library and, wanting to find out more about this mystery, he launches an investigation to figure out what is making her invisible to everyone.

SOMETIMES MORE IS JUST CRAZY!Just before summer break, Sakuta encounters Shouko Makinohara, a girl in junior high with the same name and face as his first love. Of course, that should be impossible, since she would be in college by now. Then, as if one mystery wasn't bad enough, Adolescence Syndrome strikes again. His impassive friend from the science club, Rio, discovers she has a doppelgänger. One of the Rios is forced out of her house and winds up staying at Sakuta's apartment. Definitely not the girl he expected to find himself living with...And when Mai insists she's going to sleep over, too, Sakuta's summer vacation descends into pure chaos.

DOUBLE TROUBLE?! ​Sakuta is eager to finally have a chance to spend time with Mai again, but instead, he's greeted by a stranger who looks just like her. Apparently, Adolescence Syndrome is paying Mai another visit and has forced her to swap bodies with Nodoka Toyohama, a flashy up-and-coming idol...who also happens to be Mai's half sister! With no resolution in sight, each sister must pretend to be the other and go about their respective lives as best they can. Trouble is, it seems like Nodoka is preoccupied with something besides walking in Mai's shoes...

How far can a fake relationship go? Mai is no longer invisible--she's acting again, and she finally said yes when Sakuta asked her out for the millionth time. Life couldn't be better for Sakuta...until he wakes up and finds himself reliving the morning before she agreed to date him! Assuming this weird time slip to be another case of Adolescence Syndrome, Sakuta begins searching for clues and stumbles upon the first-year Tomoe. Though the last time they saw each other involved getting kicked in the butt, now she's desperately trying to avoid getting asked out by the boy her friend is crushing on so she won't be ostracized. One ruse leads to another, and soon news spreads that Sakuta is Tomoe's boyfriend. Now how is he going to explain this to Mai...?

Ritsu is willing to do anything for her best friend Ichika, including the intimate act of cleaning her ears. But when Ichika starts dating a boy, Ritsu realizes that she wants to be more than friends. Will Ichika push her away when Ritsu reveals her innermost feelings?