Doujinshi Volume 13

Volume 13 (お兄ちゃんはおしまい!⑬, Onii-chan wa Oshimai!⑬) is the thirteenth doujinshi volume of Onimai: I'm Now Your Sister!. It was originally released on May 2, 2020.

Trivia
第十三卷
 * This is the first volume of the doujinshi to be given a simultaneous general release.