Paradise of Innocence (2014)
Original title: 無邪気の楽園
Paradise of Innocence is a 2014 Japanese-language animation series. It stars Yasuaki Takumi, Mayuka Nomura and Sachie Hirai.
Shouta is sent back in time to his elementary school days via a mysterious school pool. He sees Konomi, a girl who would eventually become a nationally popular actress, and other cute girls when they were innocent and defenseless.