The OVA, bundled with the special edition version of the seventh manga volume, will tell an "other side" story centered on Mafuyu Satou and Ritsuka Uenoyama that wasn't featured in the movie.

Shipped with special edition of Atto's spin-off manga , the OVA serves as the 13th episode of third anime season .

The third season of .

In a certain world bubble, the conflict between the armed dolls and the dead soldiers is never ending. With the conflict between the two escalating, the stability of the world bubble is gradually decreasing. To save the world from collapse, human beings set up a special organization to manage and control the dolls. In order to cover up the dark truth, human specially gave the organization a very cute name: "Renou Xueyuan" - "Doll School". —Ahaha, just kidding! How could it possibly be anything like that? (Source: Official Weibo)