What Are You Doing!? Big Brother!!

Nani Suru no!? Onii-chan!! is a manga collection of nine short stories originally published between March 2018 and May 2019. The included chapters are "Warui Imouto ni wa Oshioki wo" ("My Little Sister Needs to be Punished!"), "Yuka no Natsuyasumi" ("Yuka's Summer Vacation"), "Imouto wa Mutonchaku" ("My Little Sister is Careless"), "Imouto no Tomodachi ni" ("To My Little Sister's Friend"), "Imouto no Mune wa Seichouki" ("My Little Sister's Chest is in a Growth Period"), "Hentai Ani ni Goyoujin" ("Beware of the Perverted Older Brother"), "Shuukaku Biyori" ("Harvest Weather"), "Tanoshii Bangohan" ("Fun Dinner"), and "Bokujou no Oshigoto" ("Farm Work"). Each chapter presents a standalone sibling-focused story, as reflected by the original Japanese and English chapter titles.