Spaghetti Napolitan is a popular Japanese pasta dish that originated from the Italian spaghetti. It is a simple yet flavorful dish made with spaghetti noodles, sautéed onions, bell peppers, and sliced sausages or bacon. The noodles are cooked al dente and then tossed in a tangy ketchup-based sauce. Spaghetti Napolitan is a quick and easy meal that is loved by both kids and adults alike.