This character is from the otome Wizardess Heart. 

Mischa is a white cat who wears a pointed hat that an ancient Wizardess would wear, and is described to be "an awfully stern cat" by the protagonist. She's cat-like familiar and hates to be referred to as just a cat or a pet. It was unknown whose familiar she was until Hugo Peers' route, when she introduced her master Vain. Mischa is acting as a spy for her master Vain. She is making sure that Hugo continues his mission and she makes note of new information regarding the protagonist and her friends. 

In Caesar's route, she seems to keep the protagonist company when she has difficult times, such as when she has to hide Caesar from his former circus boss/owner. Mischa gives the protagonist some advise on her feelings for Caesar.

Mischa has a habit of saying whatever comes to mind, even if it is a bit rude. However, she ends up caring about the protagonist and her friends a great deal but would never admit it. Now, Mischa truly feels guilty for betraying the protagonist and understands that she may no longer trust her. Even so, she tries to convince the protagonist that Hugo is not a bad guy. She also seems to care about Hugo as if he were her younger brother, and tries to look out for him. 

Voice: Slightly proud, high to mid-deep pitch, possibly cute. The cute part isn't absolutely required. It is just slightly preferred due to this being stated in the game's lore. 

Example #1, Example #2