Overview
Namekuji (or Forest Ghost) is some NPCs that drooling, slug-like creatures whose essence 'sticks' to Madotsuki when she touches them in the Forest World. There have two types of them: first type is purple outline, yellow eyelash and vomiting green liquid; another type is pink outline, white eyelid and vomiting maroon liquid.
Interaction
Interact with them directly will show their wiggling shadow stick on Madotsuki's head (or being possessed), their shadow will follow Madotsuki anywhere in the Forest World unless she goes to another map.
They don't react with any of the effects because they are a part of the chipset background of the Forest World.