Kazu is the little brother of Akira Hayame(more commonly known as the .hacker Blackrose) who is comatose for most of the Second Network Crisis presumably having encountered Skeith The Terror of Death after his sister picked out "Hidden Forbidden Holy Ground",the Chaos Gate Address for the Hulle Granz Cathedral. In Legend of the Twilight it is revealed he knew Shugo and Rena, and became an apprentice of Helba's when he came to the cast's rescue fighting off the Cobalt Knights with Ouka after handing them a key which will transport them to Netslum so Shugo can return Zefie to Aura.