Shuichi is a third year high school student and wants to be normal person and wants things to stay the same forever. but he is scared of himself as he has the ability to turn into a monster.
His abilities allows him to transform into a mascot character which gives him enhanced physical strength and sense of smell. It also has a zipper which can be unzipped so that someone can go inside of him. This will allow that person to control Shuichi's body.
If he and the person inside of him have the same goals, he can collaborate with them and join forces and fuse together to become one being and their soul, body and memories will be connected and they will be able to overcome their limits.