Wu Clan

The Wu Clan (, Ū-Yīzū) is a Chinese clan of assassins who are related to the Kure Clan.

About
As inferred by a member of the Wu Clan, the Kure Clan is the Japanese offshoot of the Wu, who arrived to Japan around a millenium ago. With exception to certain individuals, the rest of the Wu Clan still maintains a cordial relation with their Kure counterparts.

Guihun (, Guifun; lit. Demon Spirit)
The Wu Clan's name for the Removal. Just like the Removal, this technique allows the user to unleash his latent power by removing the psychological limits from their brain. Theoretically, anyone can remove their limits with this technique, but only the Wu and the Kure have bred for generations to unleash one's full strength without causing harm or killing one's self. The only known outsider who can use Guihun is ???, who was described as that one-in-a-million prodigy who can do so, though not without any physical consequence.