Yes, there are regional differences in Japan when it comes to liking or disliking natto. Natto originated in the eastern region of Japan, particularly in the Kanto region, which includes Tokyo, and is therefore more prevalent and popular in this region. This is also the region where natto is typically served with soy sauce, karashi mustard, and chopped scallions over a bed of hot rice. In contrast, in western Japan, natto is less popular and less commonly consumed.
In the Kansai region, which includes Osaka and Kyoto, people tend to prefer other types of fermented foods, such as soy sauce and miso, over natto. In Okinawa, which is Japan's southernmost prefecture with a unique culture and cuisine, natto is not a traditional or common food, and many Okinawans may not be familiar with it or may find its taste and texture unappealing.
However, it's worth noting that these regional differences are not absolute, and there are many people throughout Japan who enjoy natto regardless of where they're from. Additionally, natto is often served in different ways and paired with various ingredients, which can affect people's preferences and enjoyment of the dish.