Ryuya Nishio is a centre-back from Osaka. He developed in Cerezo Osaka's academy and was promoted to the first team after playing for the club's under-23 side in J3. Nishio became a regular J1 League defender with Cerezo and was also involved with Japan youth teams. In 2024 he was called into Japan's squad for the AFC U-23 Asian Cup, which Japan won. He joined RB Omiya Ardija in 2026.