Yaichirō Shimogamo, eldest son of the late Sōichirō Shimogamo, inherits his father's legacy after Sōichirō is captured and consumed by the human Friday Fellows during their annual hot pot feast. As the new head of the Shimogamo family, Yaichirō aspires to become the next Nise-emon, a role demanding leadership over Kyoto's tanuki society and mediation between human, tanuki, and tengu factions. Driven by a strong sense of duty and responsibility, Yaichirō often presents a stoic and idealistic front. Yet he grapples with deep anxiety, particularly during critical moments like the Nise-emon election or family crises, which can trigger an involuntary transformation into a large tiger. This earned him the moniker "Shimogamo Tiger." Despite striving to emulate his father's composure, he frequently feels inadequate next to Sōichirō's legendary status. His relationship with his younger brothers is pivotal. Yaichirō feels burdened by their struggles: Yajirō lives as a frog in a well, consumed by guilt over their father's death; Yasaburō pursues a carefree, unpredictable existence; and Yashirō struggles to maintain his human form when frightened. Initially viewing their behaviors as obstacles to his leadership, Yaichirō grows frustrated. Over time, he learns to rely on their support, recognizing their collective strengths compensate for his vulnerabilities. This shift marks his growth from a solitary figure seeking idealized leadership into one who embraces familial collaboration, a trait distinguishing him from his father. Yaichirō possesses proficient shapeshifting abilities, with his tiger form being his most formidable. He inherits and frequently uses his father's mechanical rickshaw, pulled by a puppet driver, symbolizing his connection to Sōichirō's legacy. He demonstrates fierce protectiveness during conflicts, especially those instigated by the rival Ebisugawa tanuki family, such as intervening to defend Yashirō from bullying by his cousins Ginkaku and Kinkaku. His mother, Tōsen Shimogamo, encourages him to develop a "bigger heart," urging a balance between responsibility and emotional openness. Yaichirō's journey culminates in accepting his family's "idiot blood" – their tendency toward recklessness or eccentricity – not as a flaw but as a source of resilience. This acceptance allows him to lead without suppressing his inherent anxieties, integrating his brothers' support into his leadership style.