Chūta, a mouse from Yumemishima island, belongs to a community oppressed by the predatory Noroi Clan under their ruthless leader Noroi. His family includes his older sister Shioji and his grandfather, Elder Shuro, who leads the island’s mouse colony.

The Noroi Clan’s brutal invasion brings devastation: many island mice perish, families are shattered, and Chūta sustains injuries. These losses drive him to undertake a dangerous journey from the island, seeking allies. His goal is to recruit courageous mice to defend his homeland and its survivors.

Wounded and desperate, Chūta reaches a harbor town and encounters Gamba and his companions. He implores Gamba and Bobo (or Mampuku in later versions), detailing the Noroi Clan’s atrocities and begging for aid. Though the seasoned sailor mice hesitate upon learning their foe is Noroi, Chūta’s dire circumstances and Gamba’s own justice compel them to join his cause.

Chūta guides Gamba and the recruited mice back to Yumemishima. There, he helps rally the remaining island mice and devise strategies against the Noroi Clan. His deep familiarity with the terrain and enemy methods becomes crucial to the resistance. His actions stem from a fierce determination to shield Shioji and Elder Shuro and free their home from weasel tyranny.

Across adaptations like the 1975 anime and the 2015 3D CG film *Gamba: Gamba to Nakama-tachi*, Chūta consistently serves as the catalyst who draws the protagonists to Yumemishima by conveying its desperate plight. He personifies the innocence and vulnerability of the island’s conflict-stricken mice. The 2015 film explicitly identifies him as an "island mouse" seeking help in the city. His sister Shioji frequently appears fighting alongside him in the island’s defense.