Giro leads the Bakubaku Valley wolf pack across all story iterations. He possesses black fur and pale yellow eyes, bearing distinctive injuries from a past hunt: a missing ear and damage to one eye, inflicted by Mei's mother as she defended herself and her child. This encounter resulted in her death but left Giro permanently scarred; the extent of his ear loss varies slightly between the original books (full loss) and the television adaptation (partial loss).

He inherited leadership following the disappearance of Garuru, his best friend, the former pack alpha, and Gabu's father. Garuru vanished during a conflict with a rival pack, leading Giro to assume both leadership and the role of adoptive father to Gabu. This history shapes his later conflicted actions toward Gabu. As pack leader, Giro enforces strict codes, prohibiting solitary hunting and mandating that wolves prioritize the pack's survival above all else. He views goats solely as natural enemies and resources, declaring wolves and goats "are natural enemies" and forbidding any association.

Giro's leadership blends pragmatism with ruthlessness. He meticulously organizes hunts, especially before winter, emphasizing capturing prey "at all costs." When Gabu's secret friendship with Mei is discovered, Giro bypasses the pack's death penalty out of loyalty to Garuru. Instead, he devises a plan for Gabu to betray Mei by extracting information about the goat herd's vulnerabilities. After Gabu rejects this and flees with Mei, Giro perceives profound betrayal. He personally leads the pursuit, driven by a need to enforce pack law and rectify his earlier leniency, vowing to capture them alive only to "kill them myself."

The pursuit culminates in a snowstorm confrontation on a mountain summit. Giro engages Gabu in combat, overpowering him until their struggle triggers an avalanche. Giro and his pack survive but are permanently separated from Gabu and Mei, last seen retreating to their home gorge. While his core antagonist role remains consistent, the television series *Arashi no Yoru ni: Himitsu no Tomodachi* expands his narrative. This version introduces younger wolves like Boro, whom Giro mentors, and briefly depicts non-aggressive moments, such as celebrating new pack pups. Despite these nuances, his fundamental belief in the predator-prey divide and vendetta against goats persist.