If you haven't had a Japanese curry in Japan, and you didn't make it from scratch, whatever you get will be a poor imitation. Real Japanese curry tastes both fresh, simple, vegetal and clean, and artificial, at the same time.
If you care deeply about food and you haven't been to Japan, I can't recommend it enough. As a tourist I've never been anywhere else that's so easy to have a great meal. It used to be dirt cheap to fly there if you booked in advance, but I guess inflation and time has upped the price a bit.
(cheapest east coast round-trip is JFK-NRT @ $709, with Alaskan & JAL. if you want more bang for your buck, check Skiplagged; for $823 you can spend 14 hours in Atlanta and 23 hours in Vancouver, or for $1,100 spend 21 hours in Istanbul, or 23 hours in Seoul, or for $1,231 spend 21 hours in Honolulu, or for $1,334 spend 23 hours in Honolulu and 20 hours in Osaka)