I guess it's the advertisement page for other manga. I remember that i have read some chapters of that manga long ago. I think it was about some sort of artist (poem or calligraphy?) who gets criticized and "runs" away to a little town. There he meets the little girl that's using his house as a secret base or something.
But sadly, i can't remember the name :(
And boom, just figured out that Manabu is probably an illegitimate son or something. Because frankly, he looks nothing like Mayami's father. So either an illegitimate son or a first husband who betrayed the mother or died or something. I don't think that this is the kind of series that would have something like infidelity as a part of it, so it's probably the dead/traitorous husband thing. Either way his mother is a horrible bitch, though.
I actually really liked chapter 10's iteration of Cinderella. The idea that the magic user, who actually knows Cinderella, what she puts up with, and wants to use their magic to make her happy, ends up with her instead of the Prince seems a lot deeper than "Girl meets prince, then get married cause he's royalty." I legit want to see something similar as a full series.