Kyodai Ken, Batman's old enemy from his training days, returns for one more rematch. Only this time he's got something new to use against the Bat.
Tropes in this episode include:
- Animation Bump: While the episode has its animation issues, the flashback showcasing the Kiba no Hoko has some pretty fluid animation and easily looks better than anything else in the episode.
- All for Nothing: Very nearly happens, as the scroll Kyodai has been searching for turns to dust in his hands from sheer age, nearly causing him to have a Villainous Breakdown. Unfortunately, the scroll fragment containing the Oonemuri Touch is intact enough to be salvaged.
- Ambiguous Situation: Bruce says that Yoru has no sons but Kyodai notes that Kairi is like a daughter to Yoru. He may have had no sons to pass on the knowledge of the Dangerous Forbidden Technique but if he had someone he viewed as a child of his own nonetheless then how is the audience to be certain Yoru's death did ultimately result in the loss of the knowledge of the technique? The scroll's destruction and Kyodai's own death renders the whole thing moot but there is still some ambiguity to the situation. A man has no sons but does have a surrogate daughter. Did he pass the knowledge on to her?
- Artistic Licence - Geography: Batman traces Kyodai Ken's call to a western-style street address.
- Awesome, but Impractical: The Oonemuri Touch kills instantly in one hit, but has to actually touch the person and can be stopped by simple armour.
- Awesomeness by Analysis:
- During a conversation with Alfred, Bruce reveals that Kyodai Ken can pull this—evidently, "fighting styles are like fingerprints," and since Kyodai has fought both Bruce Wayne and Batman, he's worked out that they're the same guy by examining their fighting technique.
- Batman survives the Touch of Death by analyzing Kyodai Ken's training dummy, noting where it has been struck the most, and wearing extra armor on the same spot.
- Back for the Dead: Kyodai Ken doesn't get away this time. Or survive. Not Batman's fault, though.
- Battle Strip: Kyodai pulls off his shirt for his final battle.
- Bilingual Bonus: "Oonemuri" (presumably written 大眠り) translates to English as "Big Sleep".
- The Bus Came Back: Kyodai Ken makes his return in this episode.
- Call-Forward: Kairi Tanaga, Yoru's star pupil whom Kyodai Ken kidnaps, later appears as an old lady and sensei in Batman Beyond.
- Chekhov's Volcano: The volcano, constantly smoking, has at least two establishing shots, along with a scene in a monitoring station where seismic activity is detected, before Kyodai Ken finds the scroll with the instructions for the Dangerous Forbidden Technique hidden in one of its caves. Then, he kidnaps Alfred and challenges Batman to a duel on its slopes, just before it finally erupts.
- Convection Schmonvection: Bruce Wayne battles Kyodai Ken on the slopes of an erupting volcano. The climax of the fight comes when they are separated on the rocks and Wayne throws a rope for the ninja to catch, thinking that if Kyodai jumps while he pulls he could make it. The ninja kicks the rope away, but not before giving a look that says, "I don't want your help," and possibly, "Please, don't be so stupid."
- Cross-Referenced Titles: Kyodai Ken's previous episode is called "Night of the Ninja"; this one is titled "Day of the Samurai."
- Dangerous Forbidden Technique: Kyodai Ken steals a scroll in Japan that teaches him the secret of a "deadly touch" technique. When Batman faces him off in the end, he tries to avoid being touched by him in a specific spot, which (theoretically) would cause instant death. He fails and is struck, and seemingly falls dead. He then gets up and continues the fight, eventually besting the ninja. When asked if the technique had missed somehow, he pulls out a metal plate from under his suit, which has been deformed by a strong force.
- Emphasis on "forbidden", even the guardians of the scroll, or specifically, the scrolls location, have never read it for fear of being tempted into using it. It becomes an issue when Bruce's sensei, the current guardian, can't help him with protecting himself from the Touch of Death because he doesn't know how it's performed.
- Distressed Damsel: Kairi Tanaga, abducted by Kyodai Ken to serve as a bargaining chip for the map to the Onemuri Touch. But to her credit, she does try to fight off Kyodai the moment she gets a chance.
- Distressed Dude: Kyodai kidnaps Alfred to lure Batman into a duel to the death.
- Face Death with Dignity: When the volcano erupts, Kyodai finds himself stranded in the middle of a sea of lava. He refuses Batman's offer of help, and stoically bows to Bruce before the lava engulfs him.
- Faking the Dead: Bruce pretends that the Oonemuri Touch worked on him, only to get back up once Kyodai turns his back thinking himself triumphant. Kyodai is so thrown off by Bruce's survival that the rest of the fight is almost a Curb-Stomp Battle.
- Graceful Loser: At the climax of their duel, Bruce Wayne and Kyodai are separated when the ledge they're fighting on breaks in two, leaving Kyodai stranded on a narrow precipice in a sea of magma. After rejecting Bruce's offer of help, Kyodai actually gives Bruce a respectful bow before being killed by a lava geyser.
- Gratuitous Japanese: Kairis one line of dialogue in the episode.
- Hand Seals: Kyodai Ken frequently uses this.
- Honor Before Reason: Bruce suggests giving Kyodai Ken a fake map to the Onemuri Touch. Yoru points out that while this would be prudent, it wouldn't be honorable. Batman himself - despite knowing how deadly this knowledge could be in the wrong hands - goes along with trading Kyodai the real map.
- Hostage For Macguffin: Kyodai forces Batman to give him the forbidden knowledge of the secret technique in exchange for Kairi's life.
- Martial Arts Uniform: Kairi wears her gi through the entire episode because Kyodai kidnaps her while she's training alone.
- Off-Model: This is considered by the crew to be one of the worst animated episodes of the series. Part of that has to do with the fact that the original animation studio, Lapiz Azul, went bankrupt during production. The rest of the episode, and its retakes, had to be done by Jade Animation instead.
- Pressure Point: The episode revolves around a martial art called Kiba no Hoko (The Way of the Fang), which uses precise strikes against pressure points. Batman's foe, Kyodai Ken learned its most fatal technique, the Oonemuri Touch.
- Revenge: Kyodai still wants revenge on Bruce.
- Save the Villain: Batman's second encounter with Kyodai Ken, ends with the ninja stranded on a rock in the middle of a lava flow. Despite all that has passed between them, Batman throws a line and offers to try and pull him to safety. The rescue is refused, and the ninja presumably dies seconds later.
- Secret Keeper: It's subtly implied that Yoru might have somehow worked out that Batman is Bruce Wayne.
- Sequel Episode: To "Night of the Ninja."
- Shout-Out: After the phone number trace, the machine displays "563 TEZUKA", a reference to Osamu Tezuka, the "Godfather of Anime". His name was also seen in "Moon of the Wolf".
- Tattooed Crook: Kyodai has a huge tattoo of a Japanese demon's head on his back. While a tattoo isn't a sure sign of being a criminal in the west, in Japan it's virtually a guarantee due to their cultural taboo against them, especially with tattoos of that size.
- This Cannot Be!: Kyodai's a little freaked out when he discovers that Batman survived his killing technique.
- Touch of Death: The Oonemuri Touch. Kyodai apparently learns it, though the only person we see him use it against is Batman - who protected himself in such a way that it would be useless, even if it is real.
- Walking Shirtless Scene: Kyodai Ken pulls off the top half of his ninja outfit when Batman points out the risks of fighting on a volcano, as if to make the fight even more dramatic.
Batman: This was a poor choice for a battleground, Kyodai! The volcano may claim us all!
Kyodai Ken: It does not matter! Ninja do not fear death!
- Wretched Hive: Sensei points Bruce towards a specific neighborhood which is populated by criminals and yakuza as somewhere Kyodai would likely be hiding. Sure enough...
- Your Approval Fills Me with Shame: Kyodai Ken compliments Batman on his stealth prowess, noting that he would have made a good ninja. Batman retorts that he'd prefer to follow the path of an honorable samurai, instead. Kyodai points out that Batman's methods are better suited to a ninja, to which Batman concedes the point.