Seikai

Seikai is a monk who appeared in ep 22 and chapter 72. He sensed something wrong about Kikyo and discovered that she was dead and was stealing souls to keep herself alive. One night after this discovery, he followed Kikyo and then told her that he knew she was really dead. Even though Kikyo said she'd do no harm to him, the monk attacked her with a spell which she ended up reflecting back to him fatally wounding him. Before he died he told her that living the way she is will just lead to a life of misery. His apprentice had fled when he saw his master struck down, with Sayo seeing everything.

Powers and Abilities

 * Spiritual power: Seikai was able to sense aura's like many other priests which is why he sensed that there was something wrong with Kikyo.
 * Soul Binding spell: Seikai was able to cast a spell that summoned a dragon from a golden orb he was holding with dragons carved in it. The dragon would then attack and bind the target and presumably kill it.
 * Weapons: Seiki also held a pilgrim's staff like Miroku. He was seen using exorcism scrolls as well.