A document dated 5 September 1607, purporting to be a transmission by Miyamoto Munisai of his teachings, suggests Munisai lived at least to this date. In this year, Musashi departed Nara for Edo, during which he fought a duel with a chain & sickle practitioner named Shishido Nanigashi in which Shishido was killed.
Possibly in Iga they engaged in a fight outside Shishido’s house (or on a bridge). As soon as Musashi saw a flash of sickle, he drew his short sword and pierced (possibly by throwing) his opponents chest, advancing to give a finishing stab.
Musashi may then have been attacked by watching students, subsequently routing them.
The story varies. The name Shishido Baiken first appears in Yoshikawa’s novel.