Christmas

Looking for a bl story where one of the main characters works with drugs and drugs don't work on him. Till he meets the other main character and get a collar like thing on his neck then is forced to take drugs.

I read this manga a while ago and want to reread it but I don't know the name. It was a yaoi manga where the main character was sold to a man with animal characteristic and the main character had like a slave contract that made it impossible for him to talk. It was not a colored manga that is all I remember.