Thread:B214/@comment-24502975-20140307173203/@comment-1359322-20140307174922

No, that's not really accurate. Reincarnated Devils only retain their original traits not their species. They are already considered as Devils the moment they reincarnate into a Devil not their original species.

"“Even that isn’t known. There has never been a case like this. The current you is a reincarnated Devil who reincarnated from a humanoid Dragon. Except, there is a way to stabilise it. Rather, there has been result. You understand that yourself, right?”"

- Azazel explaining to Issei

You can consider that this is Ishibumi's answer not only to Issei's current species but to all others as well.