Sumire 16-sai!! [Manga]

While bicycling to school her first day as a high school student, Renge Ohyama meets a weird girl who on closer inspection appears to be a life-sized doll—not an advanced robotic creation or even a magical doll. Rather, a scary looking middle aged man controls her movements, puppet-like, and speaks for her via ventriloquism. Unfortunately, this perverted-seeming old man and his doll happen to attend her new school. Even worse, is in the same class and sits right behind her. And it seems the doll wants to be friends?!