I am Japanese working in Hong Kong.
Yes, of course I miss Japanese food sometime and I know there are so many nice restaurant here.

But this restaurant Tonkachi is superb!

They have Tonkatsu, Sashimi, special nabe called "Shouga-shabu-shabu" and more and more.
All of them are marvelous! ( at least dishes that I ordered)

I can't choose for one recommendation. Tonkatsu is surely best in HK and Sashimi is fresh and melt away when you put them in your mouth. Shouga-shabu-shabu is really healthy and tasty. 
Taste of ginger and bit of garlic make you want to eat more and more!
I am very sure girls love that kind of taste.

This restaurant is highy recommended.