Ryo Washizu, nicknamed "Wa-san," is a classmate of Ibuki Ikaruga and a notorious delinquent celebrated for his street fighting dominance. Initially honing his skills as a boxer, he leverages this training to forge a fearsome reputation, typically navigating life as a loner with only Keita Torigaya as his friend—a companion whose observational sharpness offsets Washizu’s occasional tactical blind spots.

His history features two decisive losses to Yoichi Karasuma. During their second clash, Washizu escalates the fight by brandishing a switchblade in the manga or spiked iron knuckles in the anime, only for Yoichi to shatter the weapon bare-handed. Drawn to Ibuki by an intense crush, Washizu enrolls in the Ikaruga Dojo to pursue her proximity. He misinterprets Yoichi’s ties to Ibuki, branding him a "perverted pimp" exploiting multiple girls—including Ibuki—which fuels Washizu’s hostility despite their sporadic alliances against mutual threats.

Washizu’s romantic confessions to Ibuki invariably backfire. A pivotal blunder sees him accidentally profess his feelings to her sister, Ayame Ikaruga, sparking a recurring comedic partnership where they conspire to woo their respective crushes: Ibuki for Washizu, Yoichi for Ayame. His distorted perceptions, particularly of Ibuki, manifest as "Washizu Fantasy Channel" in the manga or "Washizu Vision" in the anime—sequences depicting Ibuki as an ethereal ideal and Yoichi as a villainous stick-figure, blending delusion with skewed reality.

Despite his rough exterior and humorous missteps, Washizu exhibits unexpected sensitivity. He evolves from isolation toward greater openness, cultivating broader social bonds while preserving his intimidating aura. This loyalty and sporadic vulnerability, especially concerning Ibuki, layers complexity beneath his delinquent persona.