Hold it! The author wants to drag out the bf misunderstanding and even throwing "grandma" problem on top of that as a distraction? That isn't exactly a good sight because it'd turn into an "actually it's a real bf lol" while everyone distracted with grandma.
I'm just having a thought of "What if the Grandma is a loli-like figure, meet up with Midori, seems like a lost child then proceed to ask about Airi"
And holy shit ain't that the case xD it just she's slightly different from what I expect, rather than a gloomy long black hair loli, she's a full blown gothic lolita lmao