Conversation so far:
who did miyamoto musashi first duel and what was the outcome?
My opponent was called Arima Kihei, a sword adept of the Shinto ryu, and I defeated him.
what was special about the duel?
CANNOTANSWER.
did he duel with anyone else?
At the age of sixteen I defeated a powerful adept by the name of Akiyama, who came from Tajima Province.

Question: who else did he fight?
Self-contained rewrite: who else did Miyamoto Musashi fight other than Arima Kihei and Akiyama?