SaintlyPervert
Given that aria has already sown seeds of prophecy where Rimaru will pop up, I foresee her causing chaos somewhere else (enables author to add a ‘new’ continent or kingdoms), therefore using another ‘prophecy bs dau’ technique, warn of portals appearing and monster invasion, to sow some chaos. Also as you have already introduced Re:Zero, I think it would be a nice idea to add Rem and Ram, but using this world’s evolution line to create them, maybe have them as the ‘face’ of Aria’s monster invasion