It aired on May 20th, 2017. While the fifth season episodes are untitled, this episode can be unofficially titled "The Final Battle" or "The End".
The episode begins with many of Jack's allies gathering around their television sets to watch a live broadcast of Aku's lair. After trolling everyone with the show's original opening monologue (complete with Mako's dialogue, sans the background music), Aku announces that he has captured Jack and plans to execute him on live television.
Initially unsure of how to finish off Jack, Aku finally decides that Ashi (still under his control) should be the one to kill him. Jack begs her to resist, but (on the surface) she appears to ignore him. As Ashi is about to stab Jack, the samurai's allies break into Aku's lair and begin attacking the demon. Seizing his chance, Jack escapes and makes a run for his sword, only to be stopped and attacked by Ashi.
Meanwhile, Aku laughs off the armies' attacks as he squashes a group of Blind Archers on Woolies, corrupting them into smaller versions of himself. Despite their best efforts, Jack's allies are slowly overwhelmed by the clones until the Scotsman and his daughters join the fray. Jack regroups with the Scotsman, who proceeds to introduce him to his many daughters. When Jack politely declines the offer to marry any one of them, he explains that he already met someone and gestures to Ashi, causing the Scotsman to question Jack's taste in women.
Following a savage beating from the Robo-Samurai, Aku goes up into the sky and releases a rain of spikes onto the army, killing most of the combatants. At the same time, Jack is swallowed by Ashi and tries once more to get through to her. After Jack confesses his love for Ashi, she finally breaks free of Aku's control. Aku then confronts Ashi, who declares that Aku isn't her father. Ashi then discovers that she still has Aku's powers and counters all of Aku's attacks against her. Realizing that she has all of Aku's powers, Ashi retrieves Jack's sword and creates a time portal to return Jack to the point when Aku sent him to the future. Being unable to stop them in time, Aku realizes in horror that for the first and last time, he has failed to stop Jack from returning to the past, and now him and Ashi are now capable of killing him in the past, which will erase his existence.
The scene then returns to the final scene of Episode I, with a defeated Aku sending Jack to the future in a last-ditch effort to save himself. As he monologues about how he and the samurai prince will meet again, Jack and Ashi appear from their portal. A stunned Aku bellows "You're back already!?" as Jack rushes in with his katana raised. Aku's efforts to fight back are in vain; he's still exhausted from his previous battle with Jack, much less one who has fifty more years of experience and training. Quickly tearing through the demon's defenses, Jack finishes the job by leaping into the air and stabbing Aku's final fragment, trapping the demon within his blade. With a mighty bellow of "NO...MORE!", Jack thrusts his sword into the ground, finally destroying Aku and his lair and escaping with Ashi just in time.
Sometime later, Jack and Ashi are about to be wed, but Ashi suddenly collapses during her procession to the altar. As Jack rushes to her side to help her and figure out what's going on, Ashi explains that due to the destruction of Aku (Ashi's biological father) in the past, she never would've existed in the first place. With that, Ashi fades away in Jack's arms, leaving behind her empty bridal kimono.
A depressed Jack mourns in the forest over Ashi's passing. Suddenly, Jack sees a ladybug, which likely reminded him of Ashi. Jack realizes that even though she's gone, he's grateful for the memories he has of her and his mood improves, knowing that there's hope for love as well and realizes that without her sacrifice, he would have never saved the universe and the future from Aku. Jack lets the ladybug fly away and smiles as the clouds part, revealing the beautiful forest below that will never again be decimated by Aku, showing that the future will be bright.
Alternate version: Samurai Jack: Battle Through Time
- Directed by
- Written by
- Storyboard by
- Casting by
- This is the official series finale of Samurai Jack.
- Many of Jack's former allies and acquaintances return from previous episodes to aid in the final battle. These include:
- All of Jack's teachers, except the Russian boyar, the Mongol warrior, the Egyptian priest and Master Chu attended his wedding with Ashi. Instead, three Shaolin monks attended on Master Chu's stead.
- It is likely they were deceased or unable to attend for some reason or another.
- Max's voice sounds rather different than in his initial appearance.
- Jack was finally able to return to the past and successfully destroy Aku for good.
- Tragically, destroying Aku came with a cost: Ashi would cease to exist since she was Aku's daughter. The same would apply to her sisters as well.
- After the past Aku's destruction, everything he was responsible for in the future was undone. This may affect the existence and life of the people in the future, since Aku, in some ways, was the catalyst for their own existence, not to mention some events that have occurred. However, since no one else will suffer from Aku's tyranny anymore, Jack actually saved every race and planet in the universe from misery under his rule.
- There is an ancient Chinese legend that links ladybugs with love. The legend goes that when a ladybug comes to call, it is a sign that a true love will pay the person a visit. Further renditions of the legend state that the number of spots on the ladybug indicate the amount of months that will pass until the person is united with his/her true love
- This also ties in with the red string of fate. According to the red string of fate, the two people connected by the red thread are destined lovers, regardless of place, time or circumstances. This magical cord may stretch or tangle, but never break. This myth is similar to the Western concept of a soulmate or a destined flame.
- The ending scene from Episode I, where Jack defeats Aku but is propelled into the future, is completely re-animated with new voice work in this episode.
- This episode reveals that Jack spent fifty years in the future, but was absent from his era for ten seconds. That means for every second that passed in Jack's time, roughly five years passed in the future.
- If 50 years and 10 seconds are exact, then the time coefficient between the two eras is 157,680,000.
- This episode also features the old opening within the episode (including Mako's narration as Aku), albeit with the horse whinny sound effect removed, and different sound effects and foley for the sword swings and the time portal.
- The final portion (from "Now the fool seeks to return to the past..." onward) is a newly animated sequence.
- Mako is credited posthumously as "Past" Aku.
- This is the second and final episode in Season 5 without the classic ending of Will.I.Am rapping "Gotta get back to the past". The first was Episode XCIX.
- Jack sees a ladybug and lets it fly on his hand before letting it fly away. This is similar to what happened at the end of Episode XCV, where Jack's treatment of a ladybug was the first thing to change Ashi's mind about where she stood in the battle between Jack and Aku.
- The tree Jack stands under in the end of the episodes is the same one Jack shows Ashi in Episode XCVI. Since Aku did not destroy it or the surrounding forest, its beauty was restored.
- It was also the first place where Ashi learned of Aku's destruction of the world.
- The tree also resembles a broken heart, symbolizing how Jack felt when Ashi was erased from the timeline.
- The Scotsman refers to his bagpipes as "The Phantom Pipes of Lagavulin." Lagavulin is the name of both a small town in Scotland and a whisky company that's located there.
- The shot of Jack mourning Ashi's death alone under a tree with his hair flowing, is similar to the introduction of Season 5 when he watches "Aku's grasp [on the] past, present and future".
- Mako being credited in this episode makes him one of the few voice actors who appeared at least once in every season.
- The female vocal at the end of the episode, "renchaku ha na hanasanai" is Japanese for "This unforgettable love I will not let go".
- The wedding scene in which Ashi vanished from existence is similar to the one in Gurren Lagann where Nia Teppelin vanished during her wedding with Simon, since her own existence was tied with that of the Anti-Spirals, similar to Ashi with Aku.
- Ashi's body disappearing forever somewhat mirrors Yamato Tribe Knight Burai's death from the 16th Super Sentai season, Kyoryu Sentai Zyuranger.
- The absence of Jack's katana in the final scene as he overlooks the beautiful valley below him is symbolic of how now that Aku has been vanquished the sword has served its purpose, effectively allowing Jack to give up the ways of the warrior both in form and in spirit.
- Jack and Ashi are the final two characters to speak in this episode, making them the final two characters in the entire franchise to speak.
- The end of this episode appears to deliberately contrast the beginning of the series. The first scene of Episode I: The Beginning showed the warped dead tree in the middle of a wasteland that served as Aku's prison; the final scene of this episode shows Jack in a beautiful forest, beneath the tree that would be the lone survivor of Aku's wrath in the now-averted future.
- There is an alternate ending to this episode in Samurai Jack: Battle Through Time.
- The The Guardian, Minions of Set, Tengu, and The White Ape Tribe are the only characters who can be officially confirmed to still exist in the past and new future after Aku's demise at the end of the story, as all others are unconfirmed.
- When Jack attacks Past Aku, Aku's eyebrows are missing in one frame.
- During the wedding, Jack's parents appeared to be the same age that they were when Jack was a little boy, whereas they were shown to be older after he had completed his training and returned to defeat Aku in the very first episode. Jack's father was also highly emaciated, due to his enslavement.
- They were likely being nursed back to health. Over time, they regained their health and strength.
The ending of the series appears to create a temporal paradox; if Aku was destroyed in the past, he wouldn't be able to visit his cult and provide the essence that impregnated The High Priestess. As a result of this, Ashi and her sisters wouldn't have been conceived and thus were erased from existence in the future; therefore, Ashi wouldn't have been able to produce a time portal that allowed Jack and herself to travel to the past so that Jack could destroy the past Aku.
One explanation for this apparent paradox is that it was Aku that created the future Jack was sent to. Since Jack has destroyed the past Aku, he has created a new future that replaces the one Aku had created and sent him to. However, this in turn would affect the existence of every single being in the previous future, and all of Jack's memories and experiences of the future he was sent to would be unmade since that future has ceased to be.
- Main article: Episode CI/Gallery