Kimchi-jjigae is a Korean staple and very popular in Japan as well. You can find kimchi-jjigae at most Korean restaurants and the ingredients are readily available at grocery stores.
To make kimchi-jjigae it’s best to use kimchi that is in juice or sauce- the sauce plays a key part in the recipe because it is used to flavor the soup.
Kimchi-jjigae is less salty than kimchi but also less spicy. The hot pepper flakes add most of the heat. I’ve got kids at home so I only use a teaspoon, but a tablespoon will yield a more “Korean-friendly” level of heat.