A hit man who mysteriously appears on Saki Tenjōin's vacation island to eliminate certain targets.It seems that he has some close connection to Golden Darkness as revealed in Chapter 150 where it is explained that he is the cause for the destruction of the organization which made Golden Darkness a weapon. His name is based on Train Heartnet's code, the "Black Cat", of the manga "Black Cat". His gun resembles Train's with only the symbol different, and he himself is based on Train Heartnet.