by the looks of things, the story is actually supernatural because of chapter 35.
It appears that Asuka and Sojiro from Mizuki senpai showed up, and their story is all about the supernatural. And since they're there, that either means their daugther teleported them to the world that the Mitsuishi-san story takes place in, or they just share the same world.
edit: also the eye color of Mitsuishi-san changing from black to red in the story is another supernatrual element too. This was more better seen with the volume 1 bonus manga that was sold with melonbook copies.
by the looks of things, the story is actually supernatural because of chapter 35.
It appears that Asuka and Sojiro from Mizuki senpai showed up, and their story is all about the supernatural. And since they're there, that either means their daugther teleported them to the world that the Mitsuishi-san story takes place in, or they just share the same world.
edit: also the eye color of Mitsuishi-san changing from black to red in the story is another supernatrual element too. This was more better seen with the volume 1 bonus manga that was sold with melonbook copies.
It's probably best to assume a lot of the story is litreal rather than exageration.
Mitsuishi-san speaks the truth a lot, so whenever she says something crazy she probably really means it, and that applies to a lot of other characters too.
edit:
random note, but Hajime seems to lie to Yuka sometimes, like he lied about only having chess to play when he had other games to play. there's some other times too when he lied to her.