Amefurikozo serves as a minor supporting character within the narrative. He is a yokai, specifically a rain spirit from Japanese folklore. Visually, he resembles a child wearing a kimono and is often depicted carrying a paper lantern or umbrella, reflecting his mythological origins.

His primary role involves assisting Nue, a renegade Mikura struggling with her need for human blood to survive. Amefurikozo helps Nue circumvent this violent necessity by stealing blood from hospital blood banks. However, this method fails to sustain Nue, ultimately requiring the protagonist Otoha's intervention.

True to his nature as a rain spirit, Amefurikozo commands the ability to conjure or control rainfall, aligning with traditional folklore depictions. His presence introduces a contrasting "ugly cute" aesthetic – a grotesque yet endearing appearance – offering moments of levity against the story's darker themes.

Amefurikozo acts as a "morality pet" for Nue, embodying innocence and a connection to the natural yokai world, countering the corruption of Mikura transformations. He symbolizes traditional yokai displaced by the central conflict. While his on-screen actions are limited to supporting Nue's subplot, his design and concept are firmly based on the established Amefuri-Kozō yokai, adapted into the anime's modern supernatural setting.