Do you know what can happen when you mess with girls? Lin Nan is scared out of his wits when he realizes that he has turned into a child. He has to go through the cycle of becoming a kid and transforming back to an adult every day. Furthermore, a strange dial that marks a countdown from 100 days has appeared on his nape.

　　该剧讲述了天才摄影师林楠在晚上7点突然变成了12岁小孩，12小时后的早上7点再次变回大人形态，叮当的变身时间却正好和林楠相反，为解开变身之谜，两个人联手寻找原因进而引发了一系列的故事。