Yukinojo

Found the part where Airi tells Yosho he has a daughter in the Shin Yosho Novel:

「あなたの娘の水穂《みなほ》です！」

Google translate

“It’s Mizuho” Minaho “of your daughter!”

Cleaned up

“Minaho is your daughter!”

Two things:

One- Minaho is spell in Kanji 水穂 but it also means Mizuho, hence 《みなほ》= Minaho

Two- the place where I took this line was a conversation between Yosho, Airi and Minaho, at the end of the novel just before the afterword.

I did not read the entire novel or the whole part, but I guess that means Yosho did not know Minaho existed until the end of the novel.