No, he's not mad. That comes from somewhere else, a memory of Ankh's intruding on the scene. A gust of air blows by the both of them, driven by a force of rage that seems much more alive than Eiji is right now--ironic, considering the source of his power--and maybe Eiji will pick up a hint of this flash of abject terror as Ankh can't help but relive it.

"Give Shingo-san back. If you don't... I'll destroy all your Cores!"

It's not an idle threat. It's something he could actually do--and would, because everything Eiji has ever said has told Ankh that he would never hesitate to take the detective's side over his.

The memory fades as quickly as it started and it takes Ankh a second to remember both how to breathe and that Eiji is still standing there... saying something, before that happened. Telling him to leave, that was it.

"...I was planning on it."