For those who are unfamiliar with this dish, kare raisu (カレーライス) is the Japanese take on India's traditional spicy curry. It's mostly sweet and very thick. The Japanese curry comes in a variety of spiciness levels and flavours (I have heard of cherry-based curry, and it's pink!). You can buy them in the form of curry roux blocks but there are also instant pre-cooked, already-in-liquid-form ones in a package, ready for consumption (just heat it beforehand).You could probably find a 'library' of instant curry packages if you go to a supermarket in Japan.
Curry rice (kare raisu, カレーライス) is one of Japan's most popular 'comfort food'. One of the reasons being its long storage period (hooray for refrigerators and microwaves!). It's definitely not the fastest food to prepare, but the method itself is pretty easy. You can just follow the descriptions on your curry roux box and bam! You're got yourself a Japanese comfort meal :D