The main antagonist of the video game Kirby's Epic Yarn. Yin-Yarn is an evil sorcerer from Patch Land. He comes to Dream Land and turns its inhabitants into yarn creatures, planning to take over both Dream Land and Patch Land.
There are roughly one-sh*t billion tropes so PLEASE look through them before adding one. Otherwise add what you like. ADDITION: PLEASE read through the trope description provided before submitting something. It's not a huge deal but too often people submit characters that don't fit just because they misinterpreted the title...
