Minoru calling Ninomae "mom" is very forced.
I'm curious about something.
Ninomae isn't "the best girl", it's Aya. But you know how romance in anime and manga is, right? Best girl never wins, it's the first interest or childhood friend or "destined pair" always wins. But here Aya is both best girl and first interest and "childhood friend". Is she also destined part? By all "rules and vices" Aya should be the one to end with Minoru, right?
I hope the author uses some sobrenatural bullshit to make her accept her son's love.
(however I already can see very well how this will not happen, Minoru will spend the flashback and with the phenomenon the love he feels, that is just his father's and will become a "normal son")