Rishu serves as a miniature hoshigami under the moon spirit Shaorin, standing 20 centimeters tall with light purple or pink hair and cyan eyes. When Shaorin's destructive tendencies prevent her from accompanying Tasuke Shichiri to school, Rishu replaces her as his telepathic protector. Her duties involve monitoring Tasuke's safety and reporting incidents to Shaorin via telepathy. Unable to speak audibly to humans, Rishu communicates by painting cartoons on palm cards with a brush. She uses distinctive speech patterns like "deshi" for "desu" and addresses Tasuke as "Tasuke-shama." Ruuan, another spirit, derisively calls her the "garbage gnome" due to her role in maintaining Tasuke's household cleanliness. Rishu exhibits steadfast loyalty and determination in her tasks. Her small stature leads to concealment during emergencies, such as hiding inside a rice cooker when Tasuke's sister visits. Though her background beyond serving Shaorin remains unexplored, her actions consistently demonstrate dedication as a guardian. She occasionally displays emotional reactions, particularly during interactions with characters like Shouko Yamanobe, who finds Rishu and other hoshigami endearing for their tiny size. Throughout the series, Rishu maintains a consistent character without significant development, functioning primarily as a support within Shaorin's protective efforts for Tasuke.