Gyuuki Yuusha is a supporting character in the anime series 'Yuuki Yuuna wa Yuusha de Aru'. Gyuuki serves as a familiar and partner to one of the main heroines, Fuu Inubouzaki. As a fairy-like, animal companion, Gyuuki provides support in battles against the Vertex, offering both tactical aid and emotional support. While not a human character, Gyuuki plays a significant role in the heroes' abilities and transformation, acting as a symbol of their connection to the Taisha and their responsibilities as heroes.