"Brother, I will kill you". Kotomi, Ko's brother from different mother. With the reason "struggle for the throne" as the next "The crown prince of Darkness". Kotoi after Ko's soul. But in another Ko's side, there was Abe no Seimei, onmyoji who came from the crown prince of darkness as well. In the presence of this two people, Ko's life changed completely. Especially with the truth of people around him involved with quarrel of this stronghold. source: mangaupdates