And with this, the harem is now official. And it seems the mother will accept it as long it's what Keita truly wants. Now, fir the exact number of girls involved...that's a different matter.
I think it's exaggerated for comedic value, to show how much the protagonist is obsessed with mamas. Probably also to ensure there will be so,e tension with the original game protagonist even now that Demonio is a good guy. I certainly don't think the daughters are lolis nor that a teenager who...
A part of me wants Tennouji's parents to start shipping hard him with their daughter in the faint hope we might get routes or harem ending.
Another part wants to stop any further progress with the losing heroines before it's too late (well, it's probably already too late...).