Shūichi "Bird" Torigai began as a delinquent granted room and board at Seiryō Academy in exchange for dining hall labor. He shared a close bond with Lan Komatsuzaki before Talon killed him, repurposing his remains into the cyborg model RX-606 through Dr. Merikus's engineering. This granted him enhanced capabilities for Talon's operations.

Residual memories drove the converted Bird to seek out Lan again. Having rebelled against Talon's control, he operated as a renegade prototype cyborg, joining resistance efforts. He aided rescue missions for captured Lan and Jin Kiryu, formed a bond with admiring Wataru Komatsuzaki, and warned Lan of Sonnet Barge's danger.

His encounters with Sonnet proved pivotal. Bird displayed authentic compassion and loyalty against Talon's manipulation, catalyzing Sonnet's rediscovery of humanity and understanding of genuine emotional bonds. By directly opposing Talon's objectives, Bird persisted as their adversary despite originating as their creation.

His arc embodies resistance against coercion and the lasting power of human connections beyond physical transformation. As a victim of Talon's experiments turned defiant operative, his journey underscores free will amid technological exploitation.