My Little Doggy

Since he was a kid, animal groomer Mamoru has been able to see animals' souls in human form. They haven't ever spoken back, though... until now! One of Mamoru's favorite customers is a tiny chihuahua called "Chappy," who Mamoru sees as a large, perpetually annoyed young man. When his owner gets hospitalized, Mamoru sneaks Chappy into his apartment - only for the tiny dog to turn into a big dude and confess that he's a werewolf!
(Source: Futekiya)
Note: Chapter count includes the one shot "COLOR" and one extra.