Chūta, a young mouse from Yumemishima, inhabits an island besieged by the tyrannical weasel Noroi. Wounded and driven by desperation, he escapes to seek reinforcements, crossing paths with Gamba and Bōbo at a harbor. His impassioned appeal to safeguard his homeland and its residents from Noroi’s violent conquest ignites Gamba’s group to mobilize allies for battle.

As Shioji’s younger brother, Chūta shares a profound sibling bond, their family lineage anchored in the leadership of Yumemishima’s elder mouse, Shuro. His history intertwines with Noroi’s brutality—marked by the eradication of the island’s shearwaters and the shattering of communal security. Serving as the spark for the protagonists’ quest, he channels unwavering resolve to shield his home, even amid his own fragility.

Later adaptations, including the 2015 film, preserve Chūta’s narrative as the engine of the central conflict, adapting his traits to fit restructured plots. While streamlining his dynamic with the core group, the film upholds his fierce opposition to Noroi’s oppression. His characterization melds the tenacity of youth with an unyielding allegiance to kin and community, underscoring resilience in the face of relentless hardship.