该片改编自在全球22个国家出刊的畅销小说家纪尧姆·米索（Guillaume Musso）的同名小说。讲述的是一位医生重返过去和数十年前的自己相遇，为了拯救已逝的恋人而往返于过去和现在的故事。金允锡饰演现在的男主人公，而卞耀汉则饰演过去年轻时的男主人公。

该剧讲述了住在同一屋檐下的外貌、性格、专业、喜欢的男生类型、恋爱方式各不相同的五名女大学生的青春故事。

One a bright spring day before a school trip, Semi, falls asleep on one side of the classroom, and suddenly awakens in tears over an ominous dream. She runs to Ha-eun, who is in the hospital after injuring her leg in a bicycle accident. Semi and Ha-eun are best friends. The film depicts a special day between the two. A spring day, puppy love, jealousy, friendship, small misunde...