Tankōbon Volume 1

Volume 1 (お兄ちゃんはおしまい!①, Onii-chan wa Oshimai!①) is the first tankōbon volume of Onimai: I'm Now Your Sister!. It is a compilation of chapters from Volume 1, Volume 2, Volume 3, and Volume 4 of the doujinshi with added bonus chapters exclusive to this release. It was originally released on June 27, 2018 in Japan, and on August 31, 2021 in North America.

Trivia
商业版漫画第一卷
 * The Official English Translation of the manga gives the name of Chapter 9.5 as this chapter as "Mahiro and Keade's Secret" officially, but lists it is "Mahiro and the Secret" in the table of contents.