I don't know i have not heard the drama tracks.. but.. if they was demons... why are they brothers when not related?

Also the information sauce i got it from said the Tsukinami (is that how the name is spelt?) brothers are demons too.... i mean.. i think they did come from the underworld.. but i assumed they was vampires from there...?? also... i could of sworn they sucked Yui's blood???

Unless rejet is doing Demons like Vampires now... i dunno... like i said... i have not heard the drama tracks.. nor have i played any of the Diabolik Lovers games.. (for Tsukinami brothers...)