Demon Slayer's Full Concentration Breathing Explained

In the popular anime "Demon Slayer," breathing is everything. In a world plagued by powerful demonic creatures possessing all types of supernatural abilities, humans struggled to find a way to combat the monsters intent on destroying them. For this purpose, many warriors have developed specialized breathing techniques that enhance their physical attributes and allow them to strike with elemental effects such as fire or lightning when combined with their swordplay. With these techniques in their arsenal, many humans have become successful and renowned demon slayers.

However, the path to mastering these techniques is difficult, and a demon slayer must learn to have full control of their breath while attacking in order to make full use of their particular style. The path to mastering this ability takes weeks or months of incredibly intense training. In the end, however, it's worth it. But while this ability, Full Concentration Breathing (or Total Concentration Breathing), is powerful, it only scratches the surface of a demon slayer's breathing techniques.

Full Concentration Breathing is much more than simply breathing deeply. The goal is for the demon slayer to inhale as much oxygen as possible so that their techniques can be used to their greatest effect. It requires such mastery and control of one's lungs that many demon slayers can only use it during the split second in which they attack their opponents. As the name implies, it takes all of their concentration just to use it in conjunction with their combat skills.

However, the most powerful demon slayers have trained themselves to bypass this fatal flaw. After undergoing much harsher training than the average demon slayer, they are able to retain the effects of FCB at all times. Regardless of whether they are sleeping or exercising, masters of this enhanced technique, known as Constant Full Concentration Breathing, always have access to its physical benefit.

Tanjiro, the protagonist of "Demon Slayer," learns this ability during the show's "Rehabilitation Arc." After a hard-fought battle, Tanjiro and his allies are taken to Butterfly Mansion, where their injuries are healed and they are taught Constant Full Concentration Breathing. Much like the standard version of FCB, Constant FCB requires rigorous training to fully master.

During his time at Butterfly Mansion, Tanjiro ran, lifted heavy weights, trained his reflexes, and even slept while maintaining conscious control of his breathing patterns. The effort required to sustain this was extremely painful at first, but over time, it became second nature. To strengthen his lungs, Tanjiro began blowing into special gourds with the eventual goal of bursting them. The final test in training for Constant FCB is to burst a gourd that stands several feet tall.

Ostensibly, the end result of this training is that Tanjiro now reaps the full benefits of FCB no matter what. For all intents and purposes, his strength, speed, and reflexes are all on par with the grand majority of demons. Though it may not be as flashy as the sword techniques that actually kill demons, Constant FCB is doubtlessly the best tool in his arsenal.