These characters are from "Ijiranaide, Nagatori-san", with the man and woman in bed being the two main characters, and the woman on left was his senpai in high school. Not going to say not poly, as there was some teasing in the manga, as well as some well known hentai, but definitely not child/sibling.

[–] orochi02@feddit.org 2 points 3 days ago (1 children)

Wait what, there was hentai?

[–] thecaptaintrout@lemmy.zip 4 points 3 days ago* (last edited 3 days ago)

There is plenty, especially as mangaka had drawn hentai before making Nagatoro. One famous one is The Joy of Breeding NSFW

[–] apotheotic@beehaw.org 0 points 3 days ago

Oh sweet I'll take that as a win