Like it says on the tin.
Miyamoto Musashi's soul takes control of his body once again, and he crawls out of his cryogenic freezer before vanishing.
Well, not really. He's sulks around with Pickle for a few months, and re-emerges in the Kengan circuit(he thinks its better than Gourouku's product because he can get better recognition, adulation, and wealth there...) He also steals his swords on the way out, and is loaded for bear.
Can the Kenganverse survive Musashi?
Can they put him back to sleep, or even put him to the sword once he gets serious(i.e. he fights like he fought the Tokyo PD, not like his back-and-forth-out-of-curiosity with Retsu, or his nutshot battle with Baki...)
GO!