He was always here though. Try to reread and you will see the hints they give mira.editz
I get it. He is contracted by the original mc and is the reason why the current mc was reincarnated. But still, there is hint to why he was contracted with that guy. And the whole contradicting tones in these last chapters makes the story a bit meh
What the heck is going on with this demon plotline. Why is he here? What the heck is happening? And now he shapeshifts?