Aoharu x Kikanjuu

Blue Spring X Machine Gun (Oneshot)
Matsuoka and Yukki were close friends who dreamed of becoming professional soccer players together. But their hopes were dashed when Yukki moved away due to family issues.
Years pass and Matsuoka is now a host while Yukki has become a hentai mangaka. Matsuoka meets Yukki again while the latter is fleeing from his editor, and is soon introduced to his childhood friend's latest obsession…

Actual Manga:
Join Tachibana, a high school girl(?), as she embarks on a new journey in the sport of "survival games," which is known as "Airsoft" in English. Includes comedic gender confusion.

Link:
AnimeNewsNetwork (anime)