Shinto

Shinto (lit. The Way of the Gods) is the spiritual style of combat praticed by divine beings, typically those individuals that reside inside of Nirvana. Most users of Shinto are born with a natural aptitude for it, however it is possible for lesser beings to transcend to a level in which they can use it, although that's extremely rare.

Overview
In a broad sense, knowing Shinto is being identified as a God or Goddess. Kami and Megami don't count because they aren't actually deities. Back when they were abundant they never called themselves that, and only became known as Gods due to the Shinigami that they produced being unable to scale their massive amount of power. Anyone who masters Shinto is far above the level of anyone with a mastery of the Zankenoski in combat, as attacks in this form are purely spiritual, and only those who have perfect spiritual control are able to combat against it.

100% Shinto
Those with 100% Shinto are actual Gods and Goddesses from Nirvana, with Zues possessing the highest possible level. While it is possible for others to achieve Shinto, it's believed that none of them can become more powerful than an actual God or Goddess. This is something stated by Zues himself, however due to Zeus' known extreme arrogance, and the fact that Joel Goldsmith, someone who has achieved 75% Shinto, having not revealed his full power yet, some believe that this is in fact untrue.