Rikka Himuro is a teenage girl with striking blue eyes and short blue hair. Standing 160 cm tall with a slim build, she has pale skin and measurements of 79-54-82 cm. She often wears nail polish and favors a practical yet stylish wardrobe featuring miniskirts, tank tops, thigh-high stockings, crop tops, bikinis, hairpins, necklaces, and uniforms.

She was formerly Kaito's neighbor at his old residence, where they developed a routine of drinking together. During one session, fueled by Kaito's frustration over another woman's rejection, they had their first sexual encounter; his abrupt aggression, stemming from that frustration and disregard for her feelings, left a negative impression and created lasting tension between them.

Despite this painful history, she harbors deep romantic feelings for Kaito. She frequently compares herself to other women, feeling particularly insecure about her bust size, which fuels her frustration. Rikka also struggles with cooking but refuses to acknowledge this weakness, persistently insisting on preparing meals. Kaito typically endures these culinary attempts as her unwilling taste-tester.

Currently, she works part-time alongside Kaito and other female colleagues at the Aloha resort, serving guests as a waitress in the tropical resort atmosphere.