The Anatomy Doll is a particular ghost that is characterized by its half and half look.
The Anatomy Doll is a life-size anatomical model of a human, commonly found in science classrooms. Like the name suggests, the Anatomy Doll has the right half of its face and body covered in muscles that would be used to show the different types. Likewise, on the left side, there appears to be 'skin', but with an open chest displaying all the different organs. The head also reveals one half of the brain. The wet, slimy sound effects of the Anatomy Doll in motion seem to suggest that, while animate, it has some of the properties of actual human organs, although when shattered it reverts to plastic and ceramic.
While unnerving, the Anatomy Doll appears to be mostly harmless, not posing a significant threat in any of the episodes. As a ghost it is solid and animate to a degree, although limited to stiff, jerky, robotic movement.
While it seems this ghost has no control over the eye painted on the 'skin', it can move the one that is connected with the muscles.
In Episode 2, Hajime kicks over a broom and shatters the doll. It is believed to be unaffected much, however, as one of the hands run off.
The Anatomy Doll could probably be found in the Science room, and although it will pursue targets, it is unknown if anything will happen as when Hajime and Satsuki were being chased, it didn't move any limbs.
The Anatomy Doll appears to be in the end credits.