Responses
Wow!! Your theory is not bad~i like it! Maybe at end there are some twisted there...well who knows(⌒▽⌒)Maybe Delkira is really related with iruma..his Son or someone that possess His blood.. still this is just my theory(づ￣ ³￣)づ
The ring of gluttony that iruma have right now is really the ring of solomon but because of the this inside the ring that eats mana it was called ring of gluttony. The thing that is inside the ring is the demon king (delkira) he was trapped inside the ring somehow. Many demons said that Delkira just vanished and no where to be found. There must be something happened in the past and became the reason why Delkira is in the ring. By the time that the ring was activated by iruma because of his rank, ali-san appeared. I think Ali-san is delkira which is revised the memory somehow and when iruma's rank was raised again at the harvest festival Delkira appeared for a moment. I think Delkira will evolve by the time iruma ranked up. That's what I think for now.