Demon Slayer's shonen combat system is evenly split between the supernatural blood arts that demons use and the sword-based breathing techniques that demon slayers employ in battle. Demon slayers only stand a chance against demons with swords made of sun-soaked ores and widely-practiced techniques modeled after elements or even animals.
Protagonist Tanjiro Kamado was taught about the water breathing technique, and he has seen insect breathing and flame breathing techniques in action too, such as when Kyojuro Rengoku faced Akaza. However, only Inosuke Hashibira uses beast breathing because he grew up in the wild and invented that technique for himself. The demon slayer corps would benefit greatly if Inosuke opened his own beast breathing school.
Inosuke's Secret Weapon Against Veteran Demons
The Demon Slayer anime made it clear that even with nichirin swords and rigorous training, demon slayers are at a serious disadvantage against demons, who boast superhuman strength and flesh regeneration. Some demons are decades or even centuries old, and no doubt the most experienced demons, such as the dreaded Upper Moons, have already seen everything the demon slayer corps has to offer. Upper-ranked demons like Akaza and Doma aren't easily surprised by ferocious flame breathing or wind breathing moves, and no doubt they've killed many slayers who tried such things against them in battle. Fortunately, humans are more creative innovators than demons are, most of all Inosuke Hashibira.
Inosuke is a hands-on tactile learner who listens to his instincts with his ESTP personality. By necessity, Inosuke learned to hone his instincts and physical senses while growing up in the wild, far from human civilization, and it has paid off. Inosuke can sense demons from a distance, such as when he "scanned" the forest where Rui's spider clan lived, and Inosuke's delicate sense of touch allows him to emulate an animal's primal unpredictability. All this, combined with Inosuke's unusual two-sword strategy, makes him the master of his own beast breathing style. So far, he is Demon Slayer's only known user of that style, making him a unique and vital asset for the demon slayer corps.
Inosuke has the advantage over most demons simply because none of them has ever seen beast breathing in action. Inosuke's style may be bluntly straightforward, but its unpredictable and feral style with two jagged swords makes it an outlier that no demon is ever prepared for. This hardly makes Inosuke invincible -- he needed help fighting the spider clan's "father," for example -- but it's still a secret weapon that he often puts to good use. An example was Inosuke's and Tanjiro's battle against Enmu in the "Mugen Train" story arc, where Enmu was wholly unprepared for Inosuke's unusually sharp instincts, senses and patented beast breathing technique.
How Inosuke Can Replicate His Success With Beast Breathing
So far in the Demon Slayer anime, Inosuke is the sole practitioner of his patented breathing style, and if he dies, it will die with him. However, the demon slayer corps is always desperate in its never-ending war with Muzan's hordes, so its leaders will take any advantage they can get. Inosuke's unique beast breathing style is a refreshing and new take on swordplay, and if other slayers could learn it, it could become the corps' best secret weapon.
The learning curve for beast breathing is steep since Inosuke had to spend years in the wild to hone his senses and instincts to develop it. Still, many anime characters have accomplished even more unlikely successes, with Avatar: The Last Airbender's Toph Beifong being an example. Toph became the world's first metalbender when she sensed the connection between earth and metal, and in expanded Avatar lore, Toph opened the very first metalbending school. Her first few students struggled, but the most talented earthbenders eventually unlocked the secrets of metalbending, all with the benefit of Toph teaching them.
With Toph's help, the world learned to bend metal, and metalbending became an uncommon but well-established art by Avatar Korra's time. If Toph can do all that, surely Inosuke can and should open his own beast breathing school and teach the most gifted demon slayers how to fight like a wild animal, complete with two fang-like swords. The demon slayer corps is evidently overdue to reinvent its core strategies and develop something new and daring, and Inosuke is the key to that. Humanity must take full advantage of its ability to create and innovate because the slayers will never defeat demons in a contest of strength vs. strength. Inosuke has changed the rules of the game, and it might just lead to Muzan's downfall.