Mujaki no Rakuen
Type: TV Series
Plot Summary: Shouta, a 25-year-old NEET, is mocked by his former female classmates who've all become successes, at their class reunion. A mysterious incident at the school pool throws him back in time and lets him deal with those same classmates back when they were fifth grade girls.
Other name: Paradise of Innocence, 無邪気の楽園