Guchuko

Guchuko is another mysterious creature that appeared in Sunao's refrigerator, and is somewhat similar to Potemayo in appearance. Guchuko is named by Kyō Takamimori shortly after she ran into Guchuko at school. The name Guchuko is derived from a small chocolate ball called a guchu which Guchuko likes to eat, and -ko (子, -ko?) added at the end, since it is a common ending for female given names in Japan. Guchuko carries an axe with a skull on it, and can fire strong energy beams from two living horns (or possibly worms) on either side of her head. She has a very self-sufficient personality, and has only partially warmed up to Kyō, who often gives Guchuko food when at school or at home; Guchuko sleeps in a tree right outside Kyō's house.

(Source: Wikipedia)