WARNING: The following article contains spoilers for Episode 24 of Demon Slayer: Kimetsu no Yaiba, "Rehabilitation Training," available now on Hulu, Crunchyroll and other anime streaming services.
Although Tanjiro Kamado has shown some powerful abilities over the course of Kimetsu no Yaiba, the introduction of the Hashira -- the strongest members of the Demon Slayer Corps -- proves that he has a long way to go in order to truly become a master swordsman. "Rehabilitation Training," the latest episode of the anime, reveals one of the secrets to the Hashira's power: A perpetual state of Total Concentration Breathing.
Introduced in the show's third episode, Total Concentration Breathing is a technique that allows warriors to increase their heart rate and blood flow in order to achieve a major boost to their strength and stamina. The technique has played a key role in the series and is fundamentally the basis for such powerful moves as Tanjiro's Water Breathing, though Zenitsu Agatsuma also used Total Concentration Breathing to keep Older Brother Spider's poison from becoming fatal.
During "Rehabilitation Training," Tanjiro, Inosuke Hashibira and Zenitsu are forced to run a gauntlet of different exercises designed to help increase their speed and durability. They have some success, but they're completely unable to beat Kanao Tsuyuri, who passed the Final Selection along with them. Although he's disheartened, Tanjiro continues to train, until he's eventually interrupted by Naho, Sumi and Kiyo, the three girls who have been working as assistants in the recovery clinic in which Tanjiro and his friends are based. The three girls reveal Hashira are constantly using Total Concentration Breathing.
At first, Tanjiro doesn't believe this is possible, but he soons start practicing. The attempt takes a major toll on his body at first, and he feels like he's going to die from the adverse physical effects brought on by his increased blood pressure. The girls then reveal Shinobu Kocho trained Kanao using a special set of harder-than-usual gourds. The goal of the training is to explode the gourds, and there are different levels. The gourd Kanao is currently able to explode is about the size of the girls.
Tanjiro still continues training, and after fifteen days he's finally seeing progress. As he meditates on a roof, Shinobu interrupts him. Shinobu shares her dream with Tanjiro, telling the young demon slayer that she wants to be able to be friends with demons. However, Shinobu doesn't believe she'll be able to, as her sister -- a kind-hearted woman -- was killed by demons. Thus, she hates them too much to believe she can ever truly befriend them. Instead, she wants Tanjiro to live out her dream. Although she's served as something of a wild card in the series so far, Shinobu seems to genuinely want to help Tanjiro succeed at finding a way to reverse the demonization process, and is happy he's training so hard.
Potentially mastering Total Concentration Breathing could open a lot of doors for Tanjiro. During the fight with the Twelve Kizuki demon Rui, one of the biggest impediments to Tanjiro's success was that he tired himself out when switching from Water Breathing to Hinokami Dance Breathing, knowing full well that any break in his momentum would cause him to totally collapse. If Tanjiro is indeed able to master Total Concentration Breathing in the same way as the Hashira, his already formidable skills would get a significant boost, becoming more effective for longer. Although he's still a long way from being able to take on someone like Muzan Kibutsuji, Tanjiro might just stand a fighting chance against the Twelve Kizuki demons that he's hunting in pursuit of a way to reverse demonization.
New subtitled episodes of Demon Slayer: Kimetsu no Yaiba air Saturdays on Hulu, Crunchyroll and other anime streaming services.