The real hero of the first Corpse Party. She is the only reason that game has a "good" ending at all. Did she also kill one of the nicest characters in the game? Yes... not like she had any control at that point though. It really annoyed me how the sequels completely removed her or delegated her to a background character.
Yuki: Yuki, brown hair, blunt bangs, low pigtails, medium hair, blue eyes, small breasts
Ghost extra: ghost girl, tattered clothes, missing left eye, glowing blue ghost