Ever since he was a kid, women have bullied Boku, which marks him so that he stays stuck in the past and becomes unable to move on with his life. One day, his childhood crush, Kasumi, invites him to her wedding. As he watches everyone around him lead a happy adult life, Boku realizes he has been left behind, causing him to wish he could start his life all over again.
Somehow, this desire comes true, and he ends up traveling back in time to his preteen days. He soon meets Sera Narumiya, his past neighbor, who frequently harassed him throughout his school days. Given an opportunity to redo his life, Boku decides to confront his past problems, but now with the mentality of an adult—this includes, of course, a more sexual approach when dealing with troublesome women.