[It's possible the Arahabaki from Chuuya's world is a very different being from the one in Mephisto's. But even if that were the case -- it's not like they have any other leads to go by.]

It changes things considerably, yes. For starters-- it means I know I can help you.

[And he's not just saying that to be cocky. He knows demons, he's knows gods... and with it being a Japanese demon, hell, he's probably offered assistance in maintaining the location where his world's version of Arahabaki still remains sealed.]

But it does add a new layer of difficulty... I don't yet know the nature of how you and Arahabaki are connected. If you are a human serving as a living seal, it would certainly explain why a summoning verse would allow you to access its power -- essentially forcing it to possess your body when using Corruption. But if you are a human serving as a vessel...

Well, that just begs the question whether you're the real Chuuya Nakahara, or simply a very confused and weakened Arahabaki.

[Enjoy your new existential crisis, Chuuya.]