Hason Tensei (Lit. He who controls damage) is a powerful yet mysterious technique known only to Kenrou of the Delta Akatsuki. He first will target an opponent. He will then make a hand movement on his body, for example, like he makes an X on his body by moving his hand on his chest. The shape of the movement is shown on the opponent as a very deep cut, like something from a sword. This cut is deep enough to even visibly display bones.
However, a lot of mystery revolves around this technique and how it does what it can do.
Also, if he focuses fire chakra into his hand when he makes the hand gesture, the cut will happen and a burn will be inflicted on the cut area with the heat of a Raijuu.