Yūjirō, a disciplined third-year junior high student, dedicated his early life to rigorous kabuki training aimed at succeeding his father. This path shattered when his father chose another successor, driving him to seek a new future through an idol audition.

His kabuki background instilled a disciplined demeanor, but the rejection left him adrift and uncertain. His first meeting with Aizo at the audition sparked immediate friction due to their contrasting personalities. Despite their differences, both passed and were mandated by President Tamura to debut as a duo unit, a requirement Yūjirō initially resisted.

During training, Yūjirō's dedication and perfectionism clashed with Aizo's spontaneity. Forced collaboration and confronting their respective family struggles, however, fostered mutual understanding. Yūjirō's guarded nature softened as he acknowledged Aizo's talents and shared his own vulnerabilities, particularly concerning his fractured relationship with his father and lost aspirations.

He prefers dogs, contrasting Aizo's fondness for cats. His height is documented as 158 cm, later updated to 161 cm. He shares a birthday, February 22, with Aizo, a detail used in their duo's branding. The evolution of their partnership culminated in co-creating their signature kiss marks, symbolizing their shift from rivals to indispensable collaborators.