The Boar-Headed, self-proclaimed "God of the Mountains," Inosuke Hashibira, is an eccentric character in Demon Slayer: Kimetsu no Yaiba. Inosuke was raised by wild boars in the mountains and created his own Breathing Technique called the Beast Breathing, which is based on wild animal instincts.
Inosuke didn’t receive any formal training, unlike Tanjiro from the former Water Pillar, or Zenitsu from the former Thunder Pillar. This leaves behind a mystery of how Inosuke managed to create a breathing technique of his own.
How Inosuke created Beast Breathing in Demon Slayer
Inosuke has a very bizarre fighting technique that mimics wild animals, which makes his movements harder to perceive for his opponents. Growing up, Inosuke survived fighting vicious demons in the mountains.
Although The Beast Breathing is a branched-out version of wind breathing, Inosuke self-taught this technique without anyone’s supervision.
Like every other swordsmanship technique that resembles an element, object, insect, or animal, Beast Breathing mimics the unpredictable movements of wild animals.
Inosuke’s combat is harder to perceive even for an Upper-Rank demon. He also possesses abnormal flexibility, where he can dislocate his bones to squeeze through difficult places like a mole.
Beast Breathing has eleven forms ranging in lethality, all of them are Inosuke’s personal creation. As Inosuke is a proficient close combatant, all his breathing techniques involve fights in close quarters with the exception of Eleventh Form: Sudden Throwing Strike.
In this form, he throws both of his blades onto his opponents in a circular motion like a projectile.
During Mount Natagumo Arc, Inosuke demonstrated his Beast Breathing's Seventh Form: Spatial Awareness technique to discern the location of the Spider Demon (Mother).
The sole reason for him being able to perform this technique quite efficiently in Demon Slayer would be his heightened sense of touch, where his skin can even feel small vibrations present in the air.
Somewhat similar to Gyomei Himejima and Genya Shinazugawa, Inosuke can also use the Repetitive Action technique, which he likes to call Boar Rush. With this technique, he can raise his concentration and draw out immense physical powers to keep up in a fight for a prolonged period.
Inosuke is the only known Demon Slayer who wields two Nichirin swords. He personally chipped his blade because it gives him the advantage to decapitate demons.
Inosuke says that “it feels like being sliced by a thousand blades.” However, wielding two blades didn’t give him trouble in aspects of mobility, as his swordsmanship is considered to be at the level of a Hashira.