Guchuko is a mysterious creature originating from the same refrigerator as Potemayo, discovered shortly after Potemayo's appearance. Standing approximately 15 centimeters tall, she bears horns on either side of her head that discharge searing energy beams when agitated or confronted. She perpetually carries a unique weapon resembling a scythe or axe adorned with a skull.

Initially aggressive and antisocial, Guchuko favors solitude and self-sufficiency. She bypasses conventional entryways by breaking through doors with her scythe before repairing them, and sleeps exclusively in a tree outside Kyō Takamimori's residence. Her bond with Kyō forms through food exchanges: he regularly offers snacks, particularly guchu chocolate balls that inspired her name, while she reciprocates by leaving animal carcasses like pigs or cows near his home.

Despite her independence, Guchuko develops limited attachment to Kyō. She blushes and exhibits jealousy when he feeds Potemayo, once attacking Potemayo in response. Kyō alone can physically hold her, occurring during vulnerable moments like extracting her from bushes or when she appears deceased. Guchuko communicates nonverbally, often uttering only "Poi~", which occasionally obscures her intentions. Her violent capabilities contrast with her diminutive size and occasional playful or mischievous demeanor.