Mujaki no Rakuen

Shouta Handa is a 25-year-old unemployed man who is tired of his monotonous life. One evening, at his class reunion, he meets all of the attractive girls who used to be his classmates. He soon discovers that they are all successful with interesting careers, and more importantly—really beautiful now, with more curves. Unfortunately, it seems that they are all aware of his boring, unsuccessful life, so they mock him and call him a loser, just like in the old days. Everything changes when Shouta goes for a walk to have a smoke and accidentally falls into the school swimming pool. This triggers a supernatural phenomenon that takes him back ten years into the past. He finds himself in the same swimming pool during swimming class, surrounded by his female classmates in bikinis. How is Shouta going to deal with their cuteness and closeness now that he is a grown man in a boy's body?