In his infant form, FU had a spherical form covered in white fur/wool with two pigtails. He had purple and black eyes, tiny golden horns, a mouth, and blue arms and legs.
After twenty years, FU has grown into a much more imposing form. He has a tall, blue humanoid figure, taller than most humans and rather slender. He has white markings all over his body, and crown-like horns that form a V shape on his head with eyeballs that move independently. His hair is tied into several giant braids, the largest ones at the back of his head. His face has black oval patterns on the cheeks and green lips. He wears a long red and turquoise cape, red pants with white stripes and fluorescent markings on the crotch area, and pointy purple boots.
When FU goes mad, his body grows purple eyes with black sclera and golden eyelids all over his body, his braids are undone, giving him a wild appearance. His horns grow larger, sharper and more twisted. He no longer has his cape, and his hands and feet turn into golden claws and talons.
For his final battle, FU's power goes out of control and twists his appearance to an even more extreme degree. He becomes a giant web of hair with golden branches, eyeballs, and shattered multi-colored mirrors. In the center of the web is a golden twisted horn with many uneven eyes around it. From time to time, he will expose his limbs; his arms are completely golden and his legs fully change into twisted talons covered in eyes. He harbors a twisted smile across his face, no nose, and all the eyes on his "crown" and his face merge together.