Rus

Rus is a Orthrus that appears in Monster Musume: Everyday Life with Monster Girls Online.

Zoological Classification
The Orthus are a humanoid species with canine attributes that appears in Greecean mythology as a two-headed, serpent-tailed sheep dog/guard dog that was slain by the hero as part of his twelve labours.

Trivia

 * She has split personality, one of which is stronger so it's in control most of the time.