Firewig is a large, intimidating centipede with a dark red shell and orange underbelly. His red face is twisted with rage and sports four orange "horns" at its sides. He has long, zig-zagged purple antennae and two sets of red arms and legs, and his spiked tail ends in a large orange "pincer" with red tips. Firewig also wears purple socks and straw sandals. On the back of his head, there are holes that blow steam out of them.
Firewig is an aggressive, wild Yo-kai that is very prone to losing his temper.
When inspiriting someone, their anger goes to its peak, which results in them getting into a rampage.