**Background:** Riko is a second year transfer student from Otonokizaka High School, who joined Uranohoshi after moving from Akihabara, Tokyo. She is in Chika Takami's class and is also neighbors with her. When Riko lived in Tokyo, she used to play the piano, practicing in the same room as former student and μ's member Maki Nishikino did at Otonokizaka. However, an incident happened at a live play on which she was unable to play the piano due to scenic panic, and since then she wasn't able to improve on her play. After moving to Uchiura, Chika learns of this in Season 1 Episode 2, and suggests that Riko should become a school idol with her and You Watanabe, in hopes it would inspire Riko. <hr> **Personality**: Riko is a reserved, kind, polite and modest girl who likes indoor activities, acting as a foil to her friends, the more energetic Chika and You. She is rather shy, but is nevertheless affable and friendly. However, while she is generally quite levelheaded, calm and mature, she often flies into a panic when under pressure, jumping to conclusions and making mistakes. Because of this, and a previous incident on which she failed to play the piano in front of a live audience, she doesn't think she's special, and doesn't want to become a school idol. However, her friend Chika drags her into it, in the hopes this would inspire her to keep playing the piano. In spite of her quiet and reserved personality, Riko has cynophobia: she loses her calm when she sees a dog (or anything she deems similar to one), to the point of moving recklessly when faced with one directly. This is commonly seen throughout most of Season 1 (starting with Episode 2) and is finally expanded upon in Season 2 Episode 5. After she and Yoshiko Tsushima temporarily take care of a dog in the same episode, her fear of dogs is revoked and she eventually understands she likes them, getting her own in Season 2 Episode 13. Riko can also be quite playful and dorky, this is especially seen with Chika, an example being when she copies Chika's "normal monster" act to help Chika combat her hopelessness in Season 2 Episode 1. Additionally, after the events of Season 2 Episode 5, her interactions with Yoshiko causes Riko to start acting like her at times and be called "Lili" (Riri) by her, which annoys Riko. (This name is derived from Lilith, a demon in Jewish mythology, and is also the double pronunciation of the first syllable of her name.) <hr> **Appearance:** Riko has a slim figure. She has burgundy hair that she ties into a half ponytail, wears two hairclips in her hair and has gold-colored eyes.

- She is a fan of doujinshi manga belonging to two niche sub-genres of kabedon and agokui, under the girls' love (ガールズラブ gāruzu rabu) or yuri (百合 yuri) genre.