[manga spoilers] the wanokingdom and zou

In chapter 700 Kinemon mentions that that they were 3 samurais heading for Zou before they ran into "disaster".

In chapter 795 Kaidos men talks about finding a samurai, which pretty much confirms that the island the remaining SH are on Zou.

Now the questions is what business does samurais from the Wano kingdom have on an island that probably are under Kaidos control? Who is this 3rd samurai and is he stronger than Kinemon since he was the only one able to reach Zou and Kinemon haven't been worried about him one bit?