Reincarnation novel. Modern world. Female MC reborns as her child self who goes to the same preschool(?) as ML. She only remembers future events one year ahead, so on. They were neighbors. ML was crippled. When MC goes to college, ML goes to a high level prison, AKA institution for bright minds gone astray, because he reported the dark organization he was in. And MC visits him every now and then. I forgot the ending and that's all I can remember.