ML hurt his head two times in a year when he was 18. During the first one, he lost all his memories of 18 years and he was confined into his room until he gained his memories. During the confinement, he kept hearing FL playing the piano and will to sneak into her room and there their romance started. But later, on the same day they started to officially date, on the way home after sneaking out, ML encountered another fight and hit his head again, this time he regained all his memories prior to the first head injury but lost all the memories he made during the time he lost his memories, which are mostly related to FL. ML didn't really think much of the lost memories during the gap since he was told that he was mostly confined in his room the whole time.