8-Gatsu 31-Nichi No Long Summer
Summary
Suzuki-kun and Takagi-san are two high school students who met in a time looping August 31st. Only the two of them keep their memories. The cause of the time loop is believed to be something Suzuki-kun has left undone over summer vacation, a teenage boy's biggest goal...A youthful time loop comedy that faces romance head-on!---- (https://morning.kodansha.co.jp/c/831longsummer.html)