Yin-Yarn is the main antagonist of Kirby's Epic Yarn for the Wii. In the beginning of the game, Dream Land's residents are terrorized by the creature. He uses his evil powers to transform everyone he comes across into yarn.
Upon stealing Yin-Yarn's Maxim Tomato, Kirby is sucked into Yin-Yarn's world via his teleporting sock. Kirby soon finds out that his entire body has been transformed into yarn and that the world in which he now resides is completely torn apart. With the assistance of Prince Fluff, a new friend, Kirby traversed the world, stitching it back together. At the end of his adventure he confronts and defeats Yin-Yarn. After Kirby defeats Yin-Yarn, Yin-Yarn's knitting needles create a more powerful robotic version of him called Mega Yin-Yarn.