In 3 seconds, regression will occur. Choi Hyun-Gyeol is trapped in a loop where, at midnight on the 15th, he reverts to the previous day. Driven mad by the 20th repetition of the same assignment, he decides to go on a quest and ends up spending the night with Lim Yeon-Jeong, a college classmate he meets by chance. The next day, he wakes up on the 15th for the first time...
(Source: AniList)