Conversation so far:
what was first duel for Miyamoto Musashi?
According to the introduction of The Book of Five Rings, Musashi states that his first successful duel was at the age of 13.
what was special about the first duel of Miyamoto Musashi?
against a samurai named Arima Kihei who fought using the Kashima Shintō-ryū style, founded by Tsukahara Bokuden

Question: did he duel with anyone else?
Self-contained rewrite: did Miyamoto Musashi duel with anyone else after Arima Kihei?