Go-Go Curry is easily the best Japanese curry I've ever had. the portions are quite large and the curry itself has a unique, vaguely sweet flavor to it.
Go go curry was just great. The portions are really big. I ordered the business class (large) katsu curry and i couldn't finish it. Next time (and i'm sure there will be a next time) i will order the economic class. All dishes come with a small portion of cabbage too, which you can enlarge for free.
The spiciness was great too, not very spicy, nor very soft, just the ideal amount for getting that hot feeling in your mouth without having to drink a cup of water after each mouthful.
If you plan to go with a big group, remember that this store has only counter seats, and its often crowded.