Ruki Mukami

Ruki is the eldest son of the Mukami family and is known as the 'Brains' of the group. When he was still a human, Ruki was the son of an aristocrat, and as a child; he was spoiled and arrogant until his family went bankrupt. He became an orphan after his father committed suicide while his mother ran away with her secret lover. This caused Ruki to distrust people since his mother never came back for him even when she told him in a letter that she still loves him. Ruki eventually ended up in the orphanage where he was bullied by the other orphans and mistreated by the staff since he was a former aristocrat, until he met his brothers, Kou, Yuma and Azusa. He devised a plan to escape the orphanage which failed when he and his brothers got shot by the orphanage staff, resulting him getting branded as 'livestock' on the back as punishment. Just as he was dying, he met the Sakamaki's father, Karlheinz, who offered him another chance to live, but as vampires. Ruki immediately accepted the offer; seeing this as a chance to get revenge on those who abused him and deprived him of humanity. As the leader of the Mukami's, Ruki is a cruel manipulator with a cool attitude who is able to keep things under his control and a bit of kuudere which Yui notices. He is often seen carrying a book around with him, which is said to be a memento of his father. He is the first from the Mukami's to drink Yui's blood in the second season of the anime. He is also rivals with Ayato and seems to enjoy taunting and provoking him when it comes to Yui.