Sōgetsu is one of Japan’s leading schools of avant-garde ikebana – Japan's centuries-old art of flower arranging. Classes are held in English on Mondays from 10am to noon; book via the web before noon of the preceding Thursday. The ¥4100 class fee includes materials. Exhibitions are sometimes held in the lobby.
Even if you have no interest in flower arranging, it’s worth taking a peek in for the building (1977) designed by Tange Kenzō, and the giant, climbable piece of installation art by the revered Japanese-American sculptor Isamu Noguchi, which occupies the lobby.