This visual novel contains at least one scene involving skull-fucking.
Skullfucking is a dark sexual act involving the penetration of head (skull) cavities except for the mouth. Among those cavities we include: eye sockets, nose holes, ears but also brain through a wound or neck if head is chopped off.
In lighter cases, the act might not end in the victim's death. Tentacles or other appendages can be inserted into the brain through the nostrils or the ears, in order to stimulate certain brain centers or for purposes of mind control.
Extremely NSFW Example Ear
Extremely NSFW Example Nose
Extremely NSFW Example Eye-Socket
Extremely NSFW Example Brain
Extremely NSFW Example Neck