The play opens at Honmaru, with Ishikirimaru writing down records about his latest mission. He even draws portraits of his comrades, which are… recognizable. He asks passing Ookurikara to pose for him and shows a half-finished picture of Nikkari Aoe as an example. Ookurikara isn't thrilled, so Ishikirimaru asks him if he will at least read the finished report. Ookurikara isn't interested in getting friendly and leaves, while Ishikirimaru muses about where will be a good point to start his story. He decides that his arrival will be the best.

The flashback shows the Saniwa calling forth a new Touken Danshi. Amidst the flames and spinning lights, from the pink steam emerges the hottie himself: Sengo Muramasa, who immediately and emphatically proclaims his desire to strip. Muramasa's revealing scene is interrupted by Tonbokiri, who is glad to see him again (even if he isn't happy about his usual flirty attitude) and offers to show him around Honmaru.

January 1543, Mikawa, Okazaki Castle. Nikkari and Ookurikara's peaceful expedition is suddenly interrupted by HRA. Okazaki Castle is under attack, with many famous people dying before the Touken Danshi can interfere. In the middle of the battle, Nikkari is entrusted with a newborn child. He is confused about what he is supposed to do, so Ookurikara warns him not to lose his focus during the battle.

At Honmaru, Tonbokiri and Muramasa run into Monoyoshi Sadamune. Muramasa flippantly says he is happy to meet Tokugawa's famous protector, and Tonbokiri asks Monoyoshi not to take it personally. Monoyoshi understands Muramasa's attitude, but before the conversation can move further, they are summoned by the Saniwa. The Saniwa explains that they have lost contact with Nikkari and Ookurikara in 1543 around Okazaki, so he assembles a mostly Tokugawa-related rescue team: Ishikirimaru (captain), Muramasa, Tonbokiri and Monoyoshi.

In the past, Ookurikara tries to talk Nikkari into leaving so Nikkari can protect the child and Ookurikara can fight alone, but the enemy forces are too dense for them to separate. Suddenly, the newcomer Muramasa appears, with Nikkari getting enthusiastic about his nudist attitude. The rest of the team catches up, and they finally manage to repel the attack. However, the problem remains: lots of important historical figures died prematurely, which even summons a Kebiishi that starts attacking the HRA.

Unaware of Kebiishi's arrival, the team catches up on their situation. Ishikirimaru is glad Nikkari didn't break in the surprise attack, but since the Matsudaira family was wiped out, this means the Tokugawa shogunate won't be established. Luckily, Monoyoshi recognizes the child: he is Takechiyo, who will later be known as Tokugawa Ieyasu. As Monoyoshi sings him a lullaby, Ishikirimaru decides what to do next: they will restore the course of history by taking the place of deceased Tokugawa vassals. Monoyoshi was always with Ieyasu, and Tonbokiri was the beloved spear of Honda Tadakatsu, so the two of them can provide detailed information about Ieyasu's life. However, Tonbokiri respects his former master too much and finds outright taking his place in history uncomfortable. Ishikirimaru understands his feelings and gives him time to think things over. Unlike others, Muramasa isn't thrilled about the "restore Tokugawa" plan and leaves to watch from afar so that he doesn't curse the baby. Ookurikara isn't interested in anything other than battle, so he leaves as well. Ishikirimaru is fine with that; after all, this is going to be a long mission, and it's for the best that everyone has different talents. Monoyoshi decides that foremost they need to rebuild the Okazaki castle, since the baby needs a home. After everyone leaves, Ishikirimaru and Nikkari talk about the baby. Nikkari is surprised that the warmth of an infant is so different from blood or his former master. Ishikirimaru is reminded of their past conversation about how Nikkari can't become a divine sword because he killed a ghost child. He argues that since Ieyasu will be deified, it means that this time Nikkari saved a divine child. Amused, Nikkari decides he will help, since the boy won't become divine if he is left alone.

Back at the present, Ishikirimaru recalls how they rebuilt the castle while taking care of the child. Monoyoshi was the main caretaker because of his love for the Tokugawas and his great parenting skills. Nikkari was also surprisingly eager to be a parent, though it was more of a curiosity thing for him. Tonbokiri was Tonbokiri, regardless of whether he had the baby with him or not. He would train while carrying the child on his back, and Ishikirimaru notes that he was probably the most father-like among them. Meanwhile, Ookurikara and Muramasa were watching them from the sides. Different sides, because Ookurikara didn't want to make friends, while Muramasa was eager to get friendly. Ishikirimaru loved rebuilding the castle with the locals, since as a sword he used to always be among people. Like this, over 10 years, Ieyasu grew from an infant into a child.

1552, Sunpu. 10-year-old Ieyasu watches a flock of birds with Nikkari and Monoyoshi and wonders if they are a family. Ieyasu becomes sad because his father was killed when he was just born, so Monoyoshi tells him to smile. Even if he goes through hard times, fortune will favour him if he smiles. Ieyasu and Monoyoshi take turns smiling and laughing together until Ieyasu feels happier.

Muramasa and Tonbokiri watch over them, discussing the roles Nikkari and Monoyoshi assumed to correct history. Tonbokiri is still uncomfortable about taking the place of his former master, while Muramasa doesn't want to get involved because of his legend. After Muramasa leaves, Tonbokiri tells passing Ookurikara about Muramasa's curse: it is believed that he wronged the Tokugawa line, killing both Ieyasu's father and grandfather.

Under a thin crescent moon, Muramasa has an awkward meeting with Nikkari. Nikkari asks him if the legends about Muramasa are true and if he hates Ieyasu. Muramasa doesn't love or hate him, he simply doesn't know what to think of him. In his eyes, Ieyasu lacks in popularity: he is very plain compared to the fierce Oda Nobunaga or the popular with masses Toyotomi Hideyoshi. And yet, he is the one who will end up in power. Nikkari admits that he grew curious about this contradiction and decided he wanted to see it through with his own eyes. Muramasa isn't interested, which Nikkari is fine with, but he notes that trying something different might be a good change of pace for Muramasa.

More years pass by. In 1555, Ieyasu reached adulthood; in 1559, his eldest son, Nobuyasu, was born; in June 1560, Imagawa Yoshimoto left Sunpu to defeat Oda Nobunaga.

Ieyasu asks Ishikirimaru to take care of his baby while he discusses strategy with his other retainers. He asks Monoyoshi what he thinks about the upcoming campaign (Battle of Okehazama). Monoyoshi predicts that, while they have a significant advantage in numbers, luck will be on Oda's side. Ieyasu isn't happy about it since Monoyoshi's predictions are never wrong, but Tonbokiri inspires him to fight anyway. Nobuyasu starts crying, so Ieyasu takes him away while talking about how he dislikes war. Newly arrived Muramasa muses how Ieyasu doesn't act like the "greatest warrior along the Tokaido" and wonders if the others screwed up while raising him, but Monoyoshi says that Ieyasu was always like that. Since they are finally going to battle, Ookurikara rejoins them, while Monoyoshi discloses their objectives.

At the foot soldiers' camp, a former farmer Gohei tries to prove he is ready for war. The samurai are picking on him until Ookurikara passes by. Gohei quickly proclaims him to be his brother, which scares the soldiers off. He asks Ookurikara what it's like to fight, because he never participated in a battle and he is scared. Ookurikara tells him not to go since people like him will only die.

Fort Marue. During the battle, Ookurikara protects Gohei. As the Touken Danshi fight, Ishikirimaru laments all the senseless deaths. Monoyoshi announces that their role in this battle is over, since Nobunaga will soon launch a surprise attack that will defeat the Imagawa side. Ookurikara isn't satisfied with the amount of fighting they did, which angers Ishikirimaru. As the two duel, Ishikirimaru notes that Ookurikara's sword is very light. Muramasa defuses the situation, just in time for Ieyasu to catch up to his retainers. This is the first time he meets Ookurikara, so Ishikirimaru introduces him as "Sakakibara Yasumasa". Ieyasu is happy to see him, because he thought he perished alongside his father, and asks him to become his retainer. Ookurikara has no choice but to agree.

After the battle, Ieyasu gained independence and allied with Nobunaga. In 1567 he changed his name to "Tokugawa Ieyasu". At the time, his son Nobuyasu was 8 years old.

Nobuyasu grew up into a kind child that likes looking after plants. He brings Ishikirimaru a flower he doesn't know. Ishikirimaru explains that it's an aconite, a poisonous plant. Nobuyasu should be practicing with a sword right now, but he doesn't like doing it. Ishikirimaru promises not to tell Ieyasu, but as a "punishment" he makes Nobuyasu repeat prayers after him. Tonbokiri, Nikkari and Monoyoshi pass by and gently remind Nobuyasu that practicing swordsmanship will help his father in the future. Nobuyasu counters that he would rather help him by growing flowers. The scene is interrupted by Gohei begging Ookurikara to teach him how to use a sword. Monoyoshi asks him why he is so eager to learn swordsmanship, and Gohei reveals his story: he is from a family of farmers; during the war, his parents died and he had to flee with his little sister, but they had nothing to eat, so his sister also died. Nobuyasu is touched by his tale and asks Ookurikara to teach both him and Gohei. After Ookurikara agrees, Nobuyasu asks Gohei why his hands are so rugged. Gohei explains that it's because he had to work in the fields since he was young, and Nobuyasu compares his own soft hands to his. After everyone leaves, Nikkari notes how kind Nobuyasu is and tries to ask Ishikirimaru about what he is going to do, but Ishikirimaru leaves before he can raise the topic.

30 July 1570, Omi. Oda-Tokugawa forces confront Azai-Asakura forces (Battle of Anegawa). Monoyoshi predicts that their side will win. Nikkari leads the van, while Tonbokiri hypes himself to reenact his former master's famous battle. Monoyoshi assures him that he will be fine, but Tonbokiri is still reluctant. Monoyoshi is a little exasperated and points out that the biggest disrespect to Honda Tadakatsu is Tonbokiri's own attitude. Obviously, Tonbokiri can't be his former master, but he only needs to be himself to express his respect for him. Tonbokiri realizes that if he doesn't participate in this battle, Tadakatsu's name won't be recorded in history, and this is utterly unforgivable. He thanks Monoyoshi for his pep talk and tells Ieyasu he is going to the enemy headquarters to kill his weak self. Tonbokiri then charges towards the advancing troops, all for victory, all for his former master. After he has claimed victory, Ieyasu gets angry with worry and tells him off, but he is glad that Tonbokiri is back and thanks him for returning alive. Muramasa snidely remarks that it's surprising for Ieyasu to be happy about someone from the Muramasa family, but Monoyoshi tells him this is how Ieyasu always was.

After the battle, Gohei trains with Ookurikara. Nobuyasu asks him to teach him how to lay out a field, because he loves plants, but no matter what he does, they wither away. Gohei happily agrees, but in return asks Nobuyasu to teach him how to read. Nobuyasu agrees and promises to learn more letters so that he can teach him even more. Ishikirimaru points out that while reading and farming are good, they are supposed to have a sword practice right now, and Nobuyasu asks Ookurikara to teach him sword alongside Gohei.

From that point, Nobuyasu started attending sword lessons more diligently and, over time, finished his studies. But the finer a person Nobuyasu became, the more Ishikirimaru was tormented by feelings of doubt. Many unpleasant thoughts plague Ishikirimaru, but he decides not to record them and tears the page where he voiced them from his report.

Now an adult, Nobuyasu trains in front of his father's retainers, just in time for Ieyasu to introduce a new one: Ii Naomasa (Muramasa). Ieyasu is worried about the upcoming battle with the Takeda forces, so his son reminds him to smile, or his luck will run out. After Nobuyasu and Gohei leave, Ieyasu thanks Ishikirimaru for raising Nobuyasu so well. After Ieyasu leaves, Nikkari tries to talk with Ishikirimaru, but Ishikirimaru excuses himself and leaves. The team is worried about him, but Ookurikara doesn't know why, so they explain: eventually, Ieyasu is going to order Nobuyasu to commit seppuku. Even Monoyoshi and Tonbokiri don't know the exact reason why, but it will torment Ieyasu for the rest of his life. Muramasa mentions some theories about Ieyasu's motives, but Monoyoshi counters that none of these rumors happened. He even wonders if this event will happen in this version of history at all, but Muramasa points out that if it doesn't, it will affect history, including his own legend, since it is believed that Nobuyasu will die by a Muramasa blade. Nikkari mentions that Ieyasu asked Hattori Hanzo to assist Nobuyasu's suicide, and the team wonders if Ishikirimaru took this role while being fully aware that this would happen.

Ieyasu calls his retainers to fight the Takeda. Monoyoshi predicts that they will win, and Nobuyasu and Gohei promise to protect Ieyasu. As the battle progresses, the HRA appear among the troops. Touken Danshi defeat most of them, but one manages to sneak up on Ieyasu. Gohei manages to cover him in time, but he is gravely injured and dies after decrying war. Ookurikara is shaken by his death, but he doesn't let others notice.

June 1575, Oda-Tokugawa forces defeated Takeda's army. Totomi was added to Ieyasu's territory, while Oda Nobunaga proclaimed himself the ruler of Japan.

In front of Gohei's grave, Ishikirimaru ponders his reasons to fight. He doesn't like battles, and he hates when people around him die. Ookurikara visits the grave while Ishikirimaru prays. They once again have a duel, but this time Ishikirimaru notes that Ookurikara's sword became heavier. After Ishikirimaru leaves, Nikkari reveals he has been watching their fight. He talks about how much Ishikirimaru dislikes battles, since he used to listen to prayers of the sick and injured people, and he prays for everyone he meets regardless of their side. Nikkari never asked Ishikirimaru why he fights, but he guesses that it's because he wants to end these wars. Ookurikara wonders if it is even possible, and Nikkari leaves after telling him he doesn't know either. Alone, Ookurikara thinks about how when they were tools, they simply fought. These new feelings are unnecessary on the battlefield. He doesn't want to be like Ishikirimaru, so he will fight by his own rules. But he does wonder what the world without wars would be like and what would happen to them in it. He has brought Gohei flowers, but decides it is too early to offer them, and instead he promises to visit again when the wars are over. After everyone leaves, Nobuyasu visits the grave to offer one last prayer.

A Kebiishi once again appears in this time period.

After a sparring, Monoyoshi hides from Muramasa, who thinks that battle is a perfect opportunity to strip regardless of whether you win or lose. Nikkari is a little offended that they were going to get nude without him. Muramasa is perfectly fine with starting stripping now, but Nikkari points out that, according to him, they need to fight first. Due to all the talk about stripping, Monoyoshi starts wondering if there is actually some merit to getting naked, much to Tonbokiri's chagrin. Ookurikara walks in on their conversation, but, after seeing Muramasa's antics, he tries to silently leave. Muramasa forces him to stay because the Tokugawa Four Heavenly Kings are finally assembled, so he wants everyone to pose for no reason. Ishikirimaru walks by, and Muramasa asks him to join their merry line, but he declines. After all, today is the day Nobuyasu is supposed to die.

Monoyoshi tries to argue with him, however, Ishikirimaru is firm in his resolve. Some people play a tragic role in history, and Nobuyasu is one of them. Monoyoshi doesn't want to accept that Ishikirimaru is going to kill an innocent person, but Ishikirimaru tells him that from his point of view, nothing justifies murder, regardless of whether the person was innocent or guilty. Monoyoshi has no choice but to accept his words, no matter how much he wishes for things to be different. Nikkari comforts him, explaining that now that they have feelings, dismissing them will just leave the Touken Danshi broken. Because of that, he is going to support Ishikirimaru in his tragic role. After a moment, Ookurikara silently follows after him, and Monoyoshi reluctantly tries to go, but he is stopped by Muramasa. Monoyoshi is a bringer of good fortune, and he should stay this way and leave the dirty work to the cursed sword. Tonbokiri reminds Muramasa that he is also a Muramasa blade, so he will support him.

5 October 1579. Nobuyasu asks Ieyasu to disown him. Gohei's death has shaken him, and he doesn't understand why someone like him had to die. Ieyasu explains it was because of his anger towards the war that took everything from him. Agitated, Nobuyasu wonders if the wars will ever end. He claims that his hands can't hold a weapon anymore, which angers Ieyasu. Ieyasu wants Nobuyasu to succeed him and won't tolerate this selfish behavior. As Ieyasu leaves, he passes by Ishikirimaru. Ishikirimaru prepares to draw his blade, while Nobuyasu muses about how wrong it feels to wage war to stop war. Nobuyasu respects his father's resolve, but simply can't accept it and asks Ishikirimaru to kill him, after he recalls the lullaby Ishikirimaru used to sing during his childhood. He doesn't consider himself an adequate successor to Ieyasu and would rather end things now. Ishikirimaru hesitates and after a few moments admits that he can't do it.

Unfortunately, Nobuyasu's survival will lead to too heavy changes in the timeline, so the team is attacked by a Kebiishi. It doesn't care if it's the Touken Danshi, the HRA or a human that survived past the moment when he was supposed to die; all of them are foreign objects in its eyes. The team engages the Kebiishi in a 6 vs. 1 battle, yet Kebiishi is still too powerful for them. Ishikirimaru manages to draw some extra strength to stall the Kebiishi, but it leaves him vulnerable. Kebiishi is about to strike him, but Nobuyasu takes the hit instead. The rest of the team fights the Kebiishi while Ishikirimaru exchanges last words with heavily injured Nobuyasu. Kebiishi almost defeats the Touken Danshi, but they manage to overpower it in the end.

1 June 1616, Sunpu Castle. Old Ieyasu is on his deathbed. Suddenly, his long-dead retainers start gathering around him. Ieyasu apologizes for making them wait for so long and thanks them for helping him build this new era of peace. Ieyasu always hated wars and didn't want to participate in them, because war only brings destruction. His family was murdered, and, ever since he was little, he expected to get killed as well. For a child, the biggest happiness is to fall asleep in the arms of their parents as they sing them lullabies, yet the Sengoku era didn't allow even such a simple thing. Even now that Ieyasu has finally built the peaceful world he always wished for, he still questions if it was worth all the blood that was spilled along the way. Ieyasu deeply regrets Nobuyasu's death and starts tearfully apologizing to him. At that moment, a person appears beside his bed. He removes his hat to reveal that he is Nobuyasu, who was actually saved by Ishikirimaru. He has abandoned his name and status and lives as Gohei the farmer now. Monoyoshi tells Ieyasu that lullabies are sung far and wide now in this peaceful world. Ieyasu is content and starts singing a lullaby from his childhood. Monoyoshi sings alongside him, until only Monoyoshi's voice remains. Nikkari tells crying Monoyoshi that he should smile. With a tearful smile, Monoyoshi tells Ieyasu that he lived a good life and wishes him to sleep well.