The realest question is how do we want it to go? Spicy scary, sugary sweet?
I kind of like scary soprano but I don't want things to go too far T_T
if she's a bit yandere but heavier on the dere side, I think I'd be down.
Maybe Mirei's got a lot of self-loathing for what she did to Soprano, and now that she's back, Soprano kinda just worms her way into Mirei's life, but not in a Parasite sort of way; just pushy, a touch domineering, but ultimately wants to reconnect because she does love our MC and wants to break down that self-loathing and make her happy (even if Mirei doesn't realize that's what she herself wants, of course).
I think it could get heavy, but hopefully not to torture/imprisonment or murder/suicide threats level or anything, yeah.
That's just my blind read based on what we've seen, but if it went that route with a happy ending that wasn't Stockholm Syndrome for Mirei, I'd be satisfied.
Like - Spicy Sweet, with a bit of a "boo!" jumpscare here or there but it's more Casper the Friendly Ghost level, not Stephen King's Misery.