Is Honey Senpai a Shota?
お爺さん or 叔父さん？



Miryoku-tekina toshiue no otoko?



An attractive older man?



Since you mentioned between the ages of 40 years an up and were asking for a term that represents the opposite of Honey Senpai's (Shota) character...



Then that would have to be an Older Man = Oji-san (uncle) or Ojiisan (old man).



It can also be used as a slightly impolite way to address a middle aged man.



If you have your doubts of such a genre existing, note that not all women prefer Shotas or Bishonens.



There is such a thing as an "Ojisan Paradise."