I do not know what medications are available in Japan, but, some common sense things to do are make sure your feet are clean and dry. You can use an antiperpirant on them (Mitchum is a decent over the counter product) Most antifungal sprays and powders are not that effective used alone. In the United States, Lamisil cream is an over the counter product now and is very effective against athlete's foot infections. Use it twice a day for a minimum of 1 week and a max of 4 weeks. You might check a local pharmacy there and see what is available.