Obviously, since milk was not traditionally used in Japan, Cream Stew must not have started as a Japanese dish, but like Curry Rice, it is now a comfort food, and pretty easy to make. (There are quite a few favorite recipes that are youshoku, western-style.) This is considered regional cooking of Hokkaido the Canada-like northern island where I was an exchange student many years ago.
This dish is my own attempt to reproduce something remembered from many years before. Typical home cooking of cream stew involves using a boxed roux, but as this product contains wheat flour, I do the white sauce from scratch. I've found that stirring in sour cream at the end results in the same rich mouth feel I remember from when I was eating wheat products and could use the commercial roux. This trick works for both Cream Stew and Curry Rice.
This recipe is a good use for leftover turkey or chicken. You can eat it plain or serve with a starch. In our house, the boys like egg noodles, which I cook in a separate pot as I can't eat them. A more traditional way to add starch is to serve with steamed rice in half the dish and stew in the other half.