This article, Hell's Seal, is property of Seireitou.

A sealing technique given to Rokudou Sennin to gaurd and was used to give humans an satanic form. The process of controlling the seal however is difficult. Fist, one must acknowledge that Satan (Luther) is the supreme God of the Universe and then the wielder must train for a long time. In the first state, the user has wine-colored seals spread all over their body. This form enhances all of their senses and speed. Once in the Second State, the user practically becomes an devel, resistant to most human made jutsu. They also become very, very dark and evil and powerful. It has a Third State but Rokudou sealed it and all knowledge of it in Seireitou Hyuga's Hell's Seal. This means that even Rokudou cannot ever remember what its secrets were.

This was taught to Seireitou only to get him prepared to achieve the Seal of Hyakuji.