In Normal Mode, Gaikottsu is spawned by the final boss as part of an attack. It moves in a straight line, disappearing upon collision with an obstacle or explosion. It will harm the player on collision.
Players who come into contact with a player who is riding Gaikottsu will obtain a Skull item. Players who ride Gaikkotsu are not affected by players who carry a Skull item.
The name "Gaikottsu" comes from the Japanese word "gaikotsu", meaning "skeleton".