Every time we go to Hong Kong, we just have to eat in a Japanese buffet restaurant. The experience is always a favorite of mine. For this trip we had to find a new restaurant as our old favorite in Tai Koo had closed it's doors. My wife's family located a hidden gem within the South China Hotel at North Point. The cost is around US $20 per adult. But that is a deal, a very good deal because buffets in Hong Kong are not like those in the US where you get cheap food that isn't fresh. The food is very good and the buffet also includes Kirin beer. Yes, I bet they hate to see Americans walk in. I can't see how they make any money at all. :-)
This one is highly recommended but I think you will need to go with someone who reads/speaks Chinese. The menu is all Chinese. They may have an English menu but we didn't ask.
Wada Japanese Restaurant
2/F South China Hotel, 67 Java Rd., North Point
This is within walking distance from the North Point MTR stop.