"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?!