A family record of 1672 says the duel did not end with one blow. Kojirō got up, Musashi's hidden pupils killed him, and Musashi fled across the strait to Moji castle. The episode follows that record, then the old man who wrote a book that never names the island.
The story follows the 1672 Numata family record, which we know only through a modern reading text. The record does not say what part Musashi had in the killing, so the film does not show it. Kojirō fighting back against the pupils is the film's own invention, where the record is silent. Episode 4 is in production and not yet released.
