Rio Kikyo is a first-year Political Science and Economics student who earned the childhood moniker 'child prodigy' through excellence in academics, sports, and music. His early ambition centered on baseball, specifically aiming for the Koshien tournament, until a pre-tournament injury permanently ended that pursuit.

He exhibits a reserved and emotionally distant demeanor, rarely revealing true feelings and appearing apathetic in social settings. This trait complicates forming close relationships. Despite his aloofness, he accepted Yuto Goryo's invitation to join band Argonavis as keyboardist. Once involved, he dedicated himself wholeheartedly to their musical activities.

As the son of a prominent Hakodate confectionery company director, Rio initially attended university there before relocating with Argonavis to Shimokitazawa for the LIVE ROYALE FESTIVAL. He transferred to Kamogawa Music College within the same faculty.

His Argonavis participation drives significant development: he learns collaborative effort and channels his dedication into the band. Though typically concealing emotions, he responds to others' needs and strives relentlessly within this collective framework. This journey marks a transition from individual athletic aspirations to shared musical commitment.