One of the Four Golden Weapons of Spinjitzu. Kai, as the ninja of Fire, was destined to wield the Sword of Fire and be its guardian. Kai retrieved it from the Fire Temple, where it was guarded by Flame the Fire Dragon. The sword was able to hurl fireballs at foes and could transform into the Blade Cycle. The Sword of Fire looked like a golden katana with a dragon head design on the hilt.