NINGENDOMO ATSUMARE!

It tells the story of Tenka Taihei, a thin little Japanese man, docile but easily manipulable, whose sperm have two flagellums and gives birth to a third human gender: neither male nor female. These “third sex” humans, born inside test tubes and mass-produced, will be used for servile purposes. (Source: FLBLB Edition, translated) — Description from AniList community (anilist.co).