Refers to Oni, monstrous foxes, gigantic earth spiders, strange beings known as Malice, and other oddities. These monsters instinctively attack humans on sight and have come to be seen as a symbol of calamity. Humans have honed their combat skills and techniques known as Kiho and passed them down to their descendents in the hope that it will help them resist the yokai menace that has long ravaged the land.

Refers to the art of controlling and manipulating the spiritual powers that reside inside oneself. Though some users fare better than others, Kiho is essentially a technique that anyone can use as long as they're willing to put in the long hours of training required to master it.

Refers to skills that involve the manipulation of huge amounts of spiritual energy. Unlike Kiho, which uses the spiritual power inside of the user, Clan Specials use the spiritual power of everything around them, allowing users to unleash incredible powers and phenomena and even harness every last bit of the spiritual power inside themselves. They are extremely delicate techniques and the Clan Specials of each of the four clans vary dramatically in terms of power and effect. These specials are similar to an instinctive talent that someone might be born with, meaning that they are largely limited to the descendants of the bloodlines that first created them.

These techniques borrow power from the Earth that pulses through it like blood through blood vessels and use it to boost the abilities of their users. Though loosely known as a technique, creating them is no harder than breathing for anyone who knows how to use them.

Hoshu Washin is a giant, continental nation, home to both humans and yokai alike. The four clans of Totsuki, Mikadoin, Oshitari, and Yakujo have survived the test of time and now rule each of the its four territories independently. The four clans are historically friends that come together to save their nation from yokai threats and have always maintained peace without dispute or conflict. Hoshu Washin was once home to a great number of other clans, but all but the remaining four were destroyed after a powerful yokai appeared hundreds of years ago.

The clan/territory which Kenshiro as well as Tatsuto Sekimizu call home. The acting ruler is Kenshiro's father, Kirihiko Totsuki. The Totsuki are renowned for their physical prowess and are skilled swordsmen and martial artists. Nevertheless, their people are usually kind and gentle.

Haruka and Sakuya's clan and the territory that they call home. The acting ruler is Haruka Mikadoin. The Mikadoin are renowned for their ability to transfer spiritual power into attacks. They also possess the ability to use Shikifuda to create pseudo lifeforms known as Shikigami and use them to do their bidding. The Mikadoin people are generally polite and elegant.

As the acting ruler of the Yakujo Clan, this is the territory that Yukari Yakujo calls home. The Yakujo are renowned for their ability to use curses to punish their victims with stat reductions and status ailments. The Yakujo people are secretive and tend to keep to themselves.

Saizo's clan and the territory that he and Chiyone Kamigakure call home. The Oshitari are renowned spies and assassins and know a number of close-range attacks that hit their opponents with status ailments. The Oshitari people are generally selfish and calculating.