Chuuta is a young mouse who comes from Yumemishima, a small island community living under the shadow of a terrible threat. His life is defined by the oppression brought by a ruthless weasel clan, led by a formidable and feared weasel named Noroi, which has devastated the mouse population on the island. As a result of these violent attacks, Chuuta suffers injuries, and his family is shattered; he lives with his older sister, Shioji, and his grandfather, Elder Shuro, who is the leader of the island's mouse colony. The desperation of his homeland, where families have been torn apart and many have perished, becomes the central force driving his actions.

In terms of personality, Chuuta is initially portrayed as someone deeply affected by trauma and hardship. He can be negative and prone to tears, overwhelmed by the dire circumstances of his people and the weight of his mission. However, beneath this fragile exterior lies a core of immense bravery and fierce determination. His willingness to leave his home and embark on a dangerous journey, wounded and alone, to find help demonstrates a quiet but powerful strength. He is not a seasoned fighter or a natural leader, but his courage is born from necessity and a profound love for his family and community. His primary motivation is purely protective: to find courageous allies who can return with him to Yumemishima, confront the Noroi clan, and free the survivors from their reign of terror.

Chuuta’s crucial role in the story is that of a catalyst. He is the character whose desperate plea for help sets the entire adventure in motion. After escaping his ravaged island, he reaches a harbor town where he encounters the adventurous mouse Gamba and his companions. Despite the fearsome reputation of the island and the weasel Noroi, which causes other mice to hesitate, Chuuta’s sincerity and the gravity of his story appeal to Gamba’s sense of justice. He serves as a guide for the recruited allies when they return to Yumemishima, using his deep familiarity with the island's terrain and knowledge of the enemy's methods to assist in planning their resistance. His relationship with his sister Shioji is a key emotional anchor; she is often seen fighting alongside him in the island's defense, and his determination to keep her and his grandfather safe fuels his resolve. Throughout the adventure, Chuuta undergoes significant development. He begins as a wounded victim in need of rescue, but his experiences and the struggles he endures alongside Gamba’s group shape him into someone notably brave. While he may not possess the raw adventurous spirit of Gamba, his journey is one of finding strength within his vulnerability and transforming from a helpless survivor into an active participant in the fight for his home. His notable ability lies not in combat, but in his unyielding spirit and his intimate knowledge of Yumemishima, which proves invaluable in the struggle against their oppressors.