It's been stuck in my head for awhile now but a couple months ago I read an amazing manga. Honestly I can't even remember the protag but he runs into a senile old man with branches in his hair who looks like he's short and round but usually just has his body tucked away somewhere (part of the gag). The old man has a branch tucked behind each ear (or maybe they were horns?) and ended up being some Celtic (maybe) god. He trains the protag how to navigate his forest domain in which time/space flows differently. The old man is in love with some forest god and they're raising their children in these plant sacs. At some point the wife and children are slaughtered (not shown) and the old man reverts to some massive humanoid deer-like form and start rampaging. It's been bugging me for a long time now, hopefully there are enough details here (and enough friendly people out here) to help me identify it.

Thanks! 😀

The manga is called Radiant by Tony Valente and was recently turned into an anime as well!! Happy readings 🙂

You're right! I had thought it was more obscure than that! I remember reading the beginning of Radiant and thinking it was nothing special and then it steadily blew my mind over and over again. Thank you so much!