Uhhh, is he really 10 years older? Or is that 'decades' older.
The former would suggest he's very talented to be 'dear friend' of dad at very young age (mid-late 20s)
The latter would fit with normal trope and explains Hesha's outrage.
There are 18 chapters(raws) in bilibili i think, but sadly only 10 are free. I liked this story too but sadly we need to wait if someones buy and translate it or if they put more free raws