Kurei is the leader of the Uruha, a group of skilled warriors hired to serve Kouran Mori and to assist Kurei in missions that Kouran orders him to undertake.

Kurei has the innate power to produce and manipulate fire. The main form of his flame is the Phoenix, and is of a purple shade. Kurei has the ability to absorb souls into his flame, and use them to produce humanoid flames that fight for him and obey his commands. His power is not limited to absorbing just one soul at a time, as shown by his absorption of several souls after an opponent slaughters many men in the latter part of the manga.

Kurei is also capable of executing non-flame based techniques such as Wakemi, a technique that allows him to produce multiple, solid duplicates of himself that possess his powers and skills. In the last part of the manga, he uses the Jikuryūri, a technique that allows its user to open a portal in time.

(Source: Wikipedia)