I don't know much about it. I think it's half and half. There are also many delicious foods in Japan, such as octopus roast and Kobe beef.
Westernization is a little bit. Japan has been deeply influenced by European and American cultures for a long time, and it is inevitable that some cultures worship it. In the eyes of many Japanese, western food is the representative of high-end and high-quality products. Watching Japanese TV dramas and cartoons, you can see the shadow of Japan being westernized in many ways. It's not just catering.
Haruki Murakami was a "die-hard fan" of European and American literature in his early years, and The Great Gatsby is one of a large number of western literary works he has read. Because of his extensive reading, his thoughts and works are also influenced to some extent. So it is not surprising that there are so many foreign IDs in Haruki Murakami's works.