Manga where a man goes to learn all about beast men culture

Question

A think he was some kinda scientist or researcher but his professor who’s be researching beast men for a long time is retiring or something and also married one of the beast men he gives the mc a book of what he knows about the beast men and the mc sets out with the professors half beast daughter. It’s a very sweet manga and the really dive into how the beast men think and talk and interact with each other,the main things I remember is that he trades with a octopus by grabbing its arm and the little beast girl is small with black hair and tail, at one point they also try to repair a house to stay in while there’s a storm and other beast men will come in and during the night one of the beast men die.I’ve been dying to find this it was so good but nothing I search up gets any decent results I really want to read it again

Answer 1

Heterogenia Linguistico is the name.

When his mentor is injured, novice linguist Hakaba is appointed to take over the professor's research in the Netherworld! Though Hakaba has studied the languages of werewolves, lizardpeople, and other Netherworld races from afar, this will be his first field experience coming face-to-face with those so many of his fellow humans have dubbed "monsters." Guided by Susuki, the professor's half-werewolf daughter (?!), Hakaba begins his quest for a greater understanding of the ways people of the Netherworld communicate-even if it does get a bit...hairy at times...!

_{(Quoted from the blurb for volume 1 on Goodreads)}