Aki is a high-held pureblood vampire who easily gets jealous of some one even close to Cana.
Aki is Cana's childhood best friend although he went missing years ago and was presumed dead in a fire that Cana blames herself for starting. Supposibly he and his younger twin, Eriya, were burned to death in a fire up on Kito Mountin.
Now seven years later, Aki has returned for the purpose of waking his brother by collecting the seven stigma; each representing the seven deadly sins. So far, Aki has only one; "Pride." Collecting these stigma is like a game and so Aki is advised and watched by Swallow, a sarcastic fellow who is strict with rules and enjoys teasing Aki.