cant remember a manga

[Thrafkroos]

i read like 2 chapters of a manga really long ago (around 3 years) where if my memory serves right: a kid transfers to a new elementary school and his new classmates all quickly pick him as their pet (or something like that) and then start messing with him and start forcing him into doing fucked up shit.
beyond that part everything else feels vague like i remember he finds a stray dog and takes care of it and when his classmates find out they murder it, overall it was pretty edgy and also it might've been a oneshot i hope i remember enough to get any answers. thanks!