Echoing the other comment. Curry powder and Asian “instant curry” are very different things. That being said, Korean and Japanese curries are very similar. You can find both in powder or “block” roux forms. Ottogi is probably the most common brand of Korean curry mix. S&B being the most common Japanese one. You can find both in most Asian grocery stores.
The main differences is in what’s put in. Koreans use more pork or beef short ribs as well as fermented or pickled veggies, like kimchi in as well. But yeah, you can put basically whatever you want in. Tofu especially, we use tofu just as often as other proteins. Kimchi Jigae or Kimchi soup, being one of my favorites.