I have been searching for a curry place in Vegas that I would always enjoy love going to and I have found it at Japanese Curry Zen.
Inside the restaurant is really small and calm, which can be desirable or undesirable, depending on the person I guess, but I don't really see it as a negative thing.
The curry itself is very tasty. When you order, I recommend getting the chicken or pork cutlet. You can even order an extra side of meat or anything else with it because they give you ample curry for another piece of meat! They even have different spices and condiments on the table for you to add to your curry so your curry won't ever be boring!
The owner always says hello and talks to customers when it isn't busy and asks if you are enjoying the food. That little bit of effort he puts to make sure everything is okay goes a long way.