@johnny_average
Doubt it if it's the average non-Christian Japanese household. Probably saying something like "Mataku" which is like verbalizing sighing in exasperation.
People hating on Nasa because he lost his memory from getting hit by a truck? Who do they think he is? Ayasaki Hayate?
And I can't hate on Tsukasa yet. We're just guessing she left from the shock he had forgotten the moment. There might be more to her leaving. I'm taking a wait and see approach.
Mom probably figures it out but at the end she'll have to play the "my old age is making me reminisce, because you remind me so much of my daughter" card.