Why did the Japanese take off their shoes in a duel?

In Japan, it has become a living habit to take off your shoes at every turn: when entering tatami rooms and visiting temples, museums and classrooms, it goes without saying that you should take off your shoes; Even if you take the Shinkansen, many people will take off their shoes, but few people let their feet out for air. Taking off shoes is a very important tradition in Japan. It is said that you must take off your shoes when you go to the holy land to worship. Only in this way can you have direct contact with the gods.