Miki is a Zashiki-warashi spirit, one of a twin pair alongside her sister Ichiko. She was taken in by Hozuki during the anime's second season. As a Zashiki-warashi, this childlike spirit belongs to a type traditionally known to bestow prosperity upon households. Her character primarily features within Peach Maki's idol agency, operating in Hell's underworld setting. Miki is employed as an idol under Peach Maki's management, with her activities and role tied directly to this depicted hellish idol industry.