"The Surprise Attack" 「忍者六儀 Ninja rokugi」 is the fifth episode of Basilisk.
Saemon Kisaragi informs Okoi that Gennosuke Kōga and Jōsuke Udono will be staying in Iga Tsubagakure for several days and Okoi gets annoyed as she wanted to go too. She feels bored and asks Saemon to come as boar bait when they go to hunt with Gyōbu Kasumi, but Saemon is not interested in boar hunting. Meanwhile, Kagerō disagrees with Gennosuke marrying a woman from Iga, but Hyōma Muroga explains that this is how he decided to achieve piece. Hyōma is worried about Gennosuke as Jūbei Jimushi had foreseen misfortune and Gyōbu suggests that he can go to Iga to check. In that moment Saemon enters and explains that he had just sent Okoi. Hyōma then hears distant footsteps and concludes they are five shinobi and they are not Kōga.
Gennosuke wonders where Jōsuke is and Akeginu explains that last night he entered her room many times and she used harsh words to tell him that she doesn't like fat gentlemen. Gennosuke starts to laugh, stating that may be good medicine for him. Oboro wonders if Tenzen and the rest had returned, but Akeginu tells her they have not.
Tenzen's group reaches a foggy Kōga, who had already prepared for their attack. Koshirō Chikuma senses someone and Rōsai Azuki gets bind to a wall. After some struggling, he manages to free himself, informing the rest that the wall told him Kōga's walls have ears. Gyōbu then announces that there are intruders and the fog disperses revealing the Iga ninja being surrounded by Kōga ninja. Tenzen tries to tell them they were sent by Gennosuke, but Gyōbu doesn't believe him considering they use a code and came from different direction. Gyōbu orders the ninja to capture them, but Iga ninja easily starts killing the Kōga ninja using their ninpō. Gyōbu reveals himself and is about to engage to engage them, when Hyōma shows up and stops him, saying that he only told him to capture suspicious people. Tenzen explains that they simply defended themselves, but it's clear how Kōga threats them and if they visit Iga someday, they will be treated the same way. Using the Hotarubi's ability, the Tenzen group escapes.
Okoi sees a suspicious man and starts chasing him, but she loses him as he leads her to a cliff from which she almost falls to her death. Meanwhile, Gennosuke asks Oboro if she could sent a messenger to Kōga as he is worried if Jōsuke had returned safely.