Rio Kikyō is a first-year Political Science and Economics student and the keyboardist for the band Argonavis. Recognized as a child prodigy excelling in academics, sports, and music, his primary aspiration was baseball until an injury just before the Kōshien tournament ended that path.

He typically maintains emotional distance, appearing apathetic in social interactions and not revealing his feelings easily. Despite this reserved nature, he accepted Yuto Goryo's invitation to join Argonavis without hesitation. Once part of the band, he committed fully to its activities, dedicating his efforts to supporting the group.

He is the son of the director of a well-known Hakodate-based confectionery company. Physically, he stands 178 cm tall, weighs 72 kg, and has gray hair with pink eyes. His birthday is November 8. His given name "Rio" combines the kanji for "dignified, severe, cold" (凛) and "raw, unprocessed" (生), while his surname "Kikyō" (桔梗) refers to the Chinese bellflower. After transferring to Kamogawa Music College, he shares the same faculty as Misaki Goto.

Regarding "Gekijōban Argonavis: Ryūsei no Obligato," the film compiles the anime series with additional new footage. His portrayal aligns with his established background and band involvement as described.