Azul absorbs 'good' energy that can hurt him, Kuro is trying to contrain Azul who absorbed the energy that would be toxic to a lessar demon...
This isn't going to go well if Kuro gets full control of Azul again...although hopefully that perfect song will distract Azul enough to get Kuro to have more control...although with people attacking Azul...
He is going to go to lose his corporeal form again and everyone is going to end up hitting each other if Kuro gets control over him again...