Series of monochrome illustrations by Kichihachi focusing on girls' breasts drawn in greyscale initially posted to his Twitter. After drawing 200 of them, he considers the ones from post #6260301 onward to be a second season. Bonus illustrations for many of the second season illustrations are available on his Fanbox.

Name in Japanese: 俺はボインちゃんが大好きでな
Originally labelled as ぱい on Twitter for the first 7 illustrations.
Also abbreviated by the artist as 俺ボ.