A living sailor uniform Ryuuko finds beneath her house. Senketsu is a Kamui (神衣 lit. "God Clothes"), an outfit that provides its wearer with godlike abilities in exchange for their blood. He has the power to transform into an indestructible suit of armor, albeit with a skimpy appearance, much to Ryūko's embarrassment. His name, given to him by Ryūko, literally means 'fresh blood'.

After defeating Kiryuuin Ragyou, while falling through the earth's stratosphere, Senketsu burns up protecting Ryuuko.