Tanjiro is brought before the Hashira and put on trial for traveling with his demon sister Nezuko.
Tropes associated with Rehabilitation Training Arc:
- The Ace: Due to being an apprentice of Shinobu, Kanao is leagues beyond Tanjiro and his trainer with the Total Concentration Breathing, of which Kanao is a master.
- Ain't Too Proud to Beg: Some of the Lower Ranks plead mercy to Muzan to be spared from him. Muzan doesn't comply.
- Arc Hero: Shinobu is the Hashira that gets the most attention in this arc, leading the rehabilitation process for Tanjiro, Zenitsu, and Inosuke. Kanao is also prominent here, helping Shinobu with rehabilitating the three boys, as well as having her backstory revealed.
- Bad Boss: If the previous arcs didn't hint Muzan is a terrible boss to work with, this arc messily reminds why Muzan is so feared by his own underlings.
- Breather Episode: Is sandwiched between the very dark Mount Natagumo Arc and the tragic Infinity Train Arc. Excluding Nezuko's trial and Muzan's demolition of the Lower Moons, nothing heavy emotional happens in this arc.
- Establishing Character Moment:
- All of the Hashiras (especially the ones introduced in the trial scene) make good impression on their personalities to Tanjiro, and to the audience.
- Giyu Tomioka's aloof and distant personality is clearly shown when he's isolating himself from the rest of the Hashiras during the trial.
- Shinobu Kocho is respectful and kind to her comrades (providing some Pet the Dog moments to Tanjiro during the trial), but she can also be ruthless when it comes to slaying demons, a prime example being Nezuko herself.
- Kyojuro Rengoku is cheerful, perhaps too happy when he declares that both Kamado siblings should be executed, alongside disagreeing with Kagaya's request to spare them.
- Tengen Uzui is all about the word "flamboyance" (or "flashy" in the dub) almost every sentence that comes out of his mouth. He's all about style when it comes to pretty much everything.
- Mitsuri Kanroji gets all affectionate towards everyone in the room, and is the only Hashira in the entirety of the franchise that never expresses hostility toward Nezuko.
- Muichiro Tokito is...rather absent minded and disinterested, randomly asking what was the bird that just showed up in the sky and claiming he'll forget the whole trial happened.
- Gyomei Hinejima is constantly in tears, openly expressing misunderstood compassionate pity towards the Kamado siblings in a prayer pose, even stating a Buddhist phrase in one of his lines.
- Obanai Iguro directs his ever-so negative attitude toward Tanjiro and Giyu, the latter because he spared Nezuko when he was supposed to kill her.
- If Sanemi Shinazugawa's hot-headed personality and deep hatred for Demons isn't enough when he outright calls Tanjiro an idiot and constantly stabs Nezuko with his sword through her box, then him sadistically tempting Nezuko to eat him while slicing blood off his arm definitely is.
- Kanao Tsuyuri's struggle to make decisions on her own is clearly shown when one of the Kakushi tries to ask her about the Butterly Estate, only to get no response in return—Aoi has to be the one doing all the greeting for her. It's made even more prevalent when she is seen with a coin that makes decisions for her.
- On the Demon side, the audience gets a taste of Enmu's sadism when he openly expresses joy of his fellow Lower Rank members killed by Muzan, even as he is ready to die by his master's hand. Muzan recognizes this and spares him with more blood before sending him off on a mission.
- All of the Hashiras (especially the ones introduced in the trial scene) make good impression on their personalities to Tanjiro, and to the audience.
- Heads or Tails?: How Kanao made her decisions before meeting Tanjiro.
- Heart Is an Awesome Power: Total Concentration Breathing, which Kanao and Shinobu note to temporarily give a highly trained human the power and speed of a Lower Rank Demon, while masters can go toe-to-toe with the Upper Ranks.
- Hero Antagonist: Sanemi is definitely on the heroes' side as a Hashira, but his antagonism towards Nezuko (and Tanjiro to a lesser extent) is easily the most prevalent. He outright mocks Tanjiro for his compassion towards his sister, and when Kagaya tries to persuade the Hashira to spare Nezuko, Sanemi slicing blood out of his arm to tempt the demon comes off as quite sadistic, even if he's really trying to prove a point out of anger.
- Jerkass Has a Point: Sanemi isn't wrong to state Nezuko is trying very hard to keep from killing humans and might slip up if the temptation is too strong.
- Kangaroo Court: It's very clear that the trial was a sham and the Hashiras would have killed Nezuko hadn't Urokodaki anticipated this and sent a letter to Kagaya.
- Only Sane Man: Mitsuri Kanroji, the Love Hashira, proposes to hear the siblings out before deciding what to do with Nezuko.
- Reasonable Authority Figure: Kagaya Ubuyashiki, who decides to listen to Nezuko and Tanjiro after hearing about Tamayo (implied to have helped him some time back), and reading Urokodaki's letter.
- Sequel Hook: The arc (and the first season) ends with Tanjiro going to the Flame Hashira for information about the Hinokami Kagura he performed against Rui.
- Sissy Villain: Muzan's second appearance has him dressed up as a woman, as he does away with the Lower Ranks.
- Training Montage: Tanjiro, Inosuke and Zenitsu train to master the Total Concentration Breathing in order to better combat The Worf Effect Rui and his clan delivered on them.
- Villain Has a Point: Despite killing most of the Lower Moon Demons is only to show his blood-thirsty Bad Boss tendencies, Muzan isn't wrong while deriding their uselessness: Kyogai, the former Lower Moon Six demon is dispatched at the hands of a rookie Demon Slayer, and Rui himself was only beheaded by a Hashira after underestimating him.
- We Hardly Knew Ye: The other Lower Ranks excluding Enmu.
- You Have Failed Me: After Rui's death, Muzan is disgusted by the Lower Ranks' tendency to die often in the hands of a Hashira, and does away with them, only sparing Enmu because he is also a vicious Sadist and liked to watch the deaths of his fellow Lower Ranks.
