From Senpai Scans:
A normal high school boy, Sagamihara Ai, picks up a suspicious doll due to the sympathy of his classmate. At that moment, he loses consciousness and when he wakes up, is standing in front of a spooky mansion. Inside that mansion, a live Alice-like doll called Mei and her teenage puppeteer, Mikael are waiting for him. Mikael tells him that the doll that brought Sagamihara to him was a doll called "Number Zero Series" made in this Workshop. There seems to be a secret about it... Unsettled, they continue to solve mysteries regarding the identity of the "Puppet Master" who has the same face as Mikael. Sagamihhara cooperates, acting as Mikael's puppet. A fantasy about a normal high school boy and a good looking puppeteer.