I was faced with five different brands of curry block when I arrived at the Japanese grocery store. Based on some online research I choose Kokumaro medium hot and then proceeded with the attempt.
Try to mix two or more different curry roux blocks. Professionals don't recommend it but many house wives do that.
My favorite combination is Java curry + Golden Curry.
I used grated apple to moderate the curry (as opposed to honey or milk).
Although there are a ton of Japanese curry recipes, I believe one of a key for good curry is onion. Saute sliced onions until they become very brown(more than 20 min) and use them as a base.
I'd estimate I got within 90% of the JAL lounge offering. I would describe the lounge curry to have have more beef flavor and the curry flavor to be more subtle than my version.
Try to get Japanese beef. You can find the beef at Japanese grocery store.
It is not a real Japanese beef(i.e. farmed in US) but it should be better than real US beef.
One discovery, my curry attempt was tastier after a day in the refrigerator.
Nice find,it's a well known fact.
Waiting 2-3 days usually get a better results.
It still needs additional work -- and further research
MO