Rereading because this is one of the only threesome manwhas I can find other than manga 
Hey....... call me Sora..
He/They
I'm DEARLY obsessed with Mob Psycho 100.
(Muskoku Tensei: Jobless Reincarnation and Tougen Anki..)
Comment by Miko on Help Me, Teacher - Chapter 1
1 Reply
@Miko there's another one called " stepping into trouble" but it only has a few chaps....