With 70 chapters up right now I feel like these theories about her being immortal or something would've caused a supernatural tag or such here or elsewhere by now if they held any real potential, but also it's a series by this author so 70 chapters might not be nearly enough to get into things like properly at all. Like 300 chapters later, "Oh yeah, I don't age. Here's a picture from when I visited another country before you were even born."
Well, whatever. I'm just gonna tunnel vision on the slice of life things for now.