Kiriya Etou is a 14-year-old third-year junior high student who frequents Seiso Academy despite not being a student there, due to his relationship as cousin to the academy's director, Akihiko Kira. He possesses dark purple hair, red eyes, and stands 1.76 meters tall.

A highly skilled violinist, Kiriya's ability rivals Len Tsukimori's, stemming from their shared childhood training alongside Shinobu Ousaki and Aoi Kaji. He exhibits extreme self-confidence and an outwardly critical attitude. Hearing Kahoko Hino practice, he deems it "a waste of time" and initially dismisses Seiso Academy's musical standards.

His abrasive demeanor shifts through repeated encounters with Kahoko. He assists her in reuniting lost twins with their mother, an event that softens his perspective. Kiriya becomes openly curious about Kahoko's opinion of him compared to Tsukimori, revealing competitiveness and hints of jealousy. He retracts his initial criticism of her playing and develops a subtle romantic interest in her, though this receives limited development in the anime adaptation *Secondo Passo*.

Kiriya's personality aligns with the "Tsundere" archetype, marked by initial hostility that shifts towards hidden concern or affection. This development is more pronounced in broader media like the *Kiniro no Corda 2: Forte* game and manga. By *Kiniro no Corda 3*, set years later, he is a 22-year-old internationally acclaimed violinist.