Muzu is one of the five castle uncles, a group of elder men who serve as trusted advisors and guardians of the Valley of the Wind. Like the other castle uncles, Muzu was once a working member of the farming community, but his hands were gradually crippled by exposure to the toxic spores of the Sea of Corruption, rendering him unable to perform agricultural labor. In his later years, he took up duties within the castle, where he helps maintain the valley's defenses and supports its leadership. Muzu's personality is marked by a gruff, serious demeanor, often wearing a stern expression that reflects his cautious and protective nature. He is deeply loyal to the valley and its people, especially to Princess Nausicaä, whom he serves with a sense of duty passed down from the reign of King Jihl. His primary motivation is the safety and continuity of the Valley of the Wind in a dangerous and decaying world. In the story, Muzu functions as part of the collective of castle uncles who act as a stabilizing presence during the crisis of the Torumekian invasion and the rampaging Ohmu herd. He does not have a personal dramatic arc or special combat skills; his role is to embody the communal resilience and quiet loyalty of the valley's older generation. His key relationships are with his fellow castle uncles, particularly Mito who serves as their leader, and with Nausicaä, whom he and the others watch over with paternal concern. Muzu does not undergo significant personal development over the course of the film, remaining a consistent background figure whose steadfastness underscores the strength of the valley's social fabric. His notable ability is his unwavering dedication to his post and his readiness to follow orders when the valley is threatened.