Poison Blade

At Yoshiwara, the 15th station, Genkurō challenges Shintarō to a duel. Okayo is his guide, so she can watch him be destroyed. The plan is that Tonbei's Iga ninja will also follow Shintarō to see if they can help leaving Sadanobu unguarded. Both Shintarō and Genkurō are wounded but Genkurō's sword had poison on it. However, Okayo gives Shintarō the antidote.