Shioji, granddaughter of Yumemishima's elder mouse Shuro, resides on the island alongside her younger brother, Chuta. As a member of the island's mouse community, she endures the violent threat of the white weasel Noroi and his clan, whose oppressive regime has ravaged the local population. Surviving Noroi's brutal attack, she remains on Yumemishima while Chuta departs seeking aid, ultimately resulting in the arrival of Gamba and his companions to defend the island. Demonstrating resilience amidst danger, Shioji challenges the notion restricting battle participation to male mice as the defenders prepare to confront Noroi, highlighting her impatience with traditional gender roles during the crisis.