(Riko is a less academically accomplished who gets worse grades than Ako in her studies as she thinks passing tests is dependent on luck, but she is very active in physical activities that she sometimes helps out with various sports clubs that need a temporarily player for training and she is a terrible cook. She has a habit of answering truthfully but very bluntly, causing everyone else to jump to conclusions. She is much shyer in person than her sister, as she cannot kiss Keita in front of anyone else; Miharu Mikuni states that Riko has more common sense than Ako.)

"Hm? Ah, hello! Keita told me you would be coming, Welcome to the Suminoe household!"