Do you know the history of curry udon? I've read various theories - that it started in the Meiji era, or in the post-war years. I find it interesting that the British are supposed to have introduced curry to Japan. Noodle curry is hardly known in Britain, but in the south of India and Sri Lanka, it's a popular dish, with rice noodles:
https://upload.wikimedia.org/wikiped...sala_Curry.jpg