This is the holy grail of the sport of Judo - the place where Jigoro Kano established his permanent school house in 1958. Unassuming entrance that looks like another office building. Free admission for visitors with a large gallery for watching practice sessions or matches. No/few signs in English but there is always someone who speaks a little English. Visitors are sometimes invited onto the mat if the have a gi for a few fast falls but normally not.
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