The manga's story centers on Aizawa, who runs into a speeding truck and time travels back to the 1990s. (Source: Anime News Network)

There are three high schools: co-ed Narayama High, all-boy Kashimori High, and all-girl Sakuragawa. Due to decreasing enrollment and financial difficulties, the three schools must be merged. However, those in charge of the reorganization could not agree on which schools to close and which to keep open. They finally decide to let the students themselves determine which school will survive. Now all the students have the chance to protect their schools, but which one will be the last one standing? The student council of Narayama High, at least, don't want to give up on their school without a fight! (Source: MangaHelpers)

I'm curious about my girlfriend's past, and I'm pretty sure I'm not alone! Ichirou, a dull guy with nothing interesting about him, has a miraculously cute and beautiful girlfriend. Her name is Yukika, and she is out of this world and wildly in love with him. At the peak of his happiness, one day he meets a man who tells him that Yukika used to be a slut. Ichiro understands in his head that his current life with his girlfriend is important, but he is caught up in a spiral of dark fantasies about his girlfriend's past. Using a VR time machine that faithfully recreates the world of the past, Ichirou makes a forbidden move...!