Akira, the series protagonist, is a participant in a fighting tournament call...
Togainu no chi
Season 1 Episode 11: Convict
Shiki fights Nicole Premier, and ends up drinking Nicole's blood, from which Line is made, which would normally drive people crazy or kill them. Shiki survives and goes looking for Akira. He finds Akira and Keisuke as they are fleeing to safety. When Shiki tries to force Akira to come with him, Keisuke tries to protect Akira, but is killed by Shiki.