Riko Suminoe is one of the main characters in the anime and manga series Kiss x Sis. She is the younger of the Suminoe twin sisters and is known for her tsundere personality—often acting tough, but with a caring and sensitive side. Riko is devoted to her stepbrother Keita, frequently competing with her twin Ako for his affection. Her role in the series centers around comedic and romantic situations that arise from her feelings and rivalry, providing much of the series’ humor and drama.