Kensuke "Ken-chan" Nimura
About
Kensuke has the same sesshōseki that transformed Yomi into an evil spirit, embedded near his heart. According to Yomi, the sesshōseki itself wished to be placed there. The stone gifts him with memories, as well as allowing his sword techniques to become radically more powerful. This stone was later removed when Imawano Setsuna forcefully tore it from his body in the Garden of Tamamo, fatally damaging his body in the process. He survived after Kagura defeated Setsuna and revived the Kyuubi, using its powers to restore his body from the brink of death. After firming his resolve to save Kagura from being controlled by the Kyuubi, he unleashes the true power of the Michael Revolution, the ability to cut through dimensions.
Kagura mentions that Kensuke has a unique presence which puts spirits at ease and even Byakuei feels more secure when Kensuke is near.
(Source: Wikipedia)
As of volumes 8 and 9, Kensuke developed a wound (and scar) over his eye after being attacked by a dark wolf demon.