Okay so I read this again and I want to re said this. Okay the younger MC is a junior high schooler or also in 9th grade. And in Japan junior students average age would be around 14 to 15 years old. And the older MC, it's stated in the manga (?) that they have a 10 year gap and also that she is a graduate of some kind of university. So that will make her around her 20's, mid 20's. (My apologies for any wrong info, but this is what I got)

I just read from another comment that the girl is 12 years old and the other woman is like around 30 years.. I don't.. I think like what the f*** I mean yeah I expected it to be like like 10 years apart but I didn't expect it to be a f****** minor a literally child what the f***. This is just oh my God what the f*** I just expected it to be cute is cuteish you know Yuri. ಠ,_」ಠ