Total Concentration Breathing (全集中の呼吸 Zen Shūchū no Kokyū?) is a breathing technique that enhances human physical traits in order to fight on par with man-eating Demons.
Total Concentration Breathing increases the user's capabilities beyond that of a normal human through advanced breathing forms. This breathing expands the user's lung capacity. This allows oxygen to reach every cell in the user's body, increasing their blood circulation and heart rate.
Taking a lot of air into the blood causes the body's temperature to spike, exciting the blood which heats up all the muscles so they can grow stronger. This enhances the user's human bodies healing factor while both stabilizing and energizing the user's spirit, allowing them to rival Demons in battle.
To properly use Total Concentration Breathing, the user must concentrate, relax their upper half and brace their lower half before taking a long breath. There can be no wasted movement during its application in combat, and this makes it difficult to master.
Total Concentration: Constant
Hashira and Tsugoku level swordsman are capable of using Total Concentration all day and night, even when they are asleep. By constantly using the breathing technique, the user's base stamina gradually grows. According to the attendants of Butterfly Mansion, being able to use Total Concentration: Constant makes all the difference in the world for a Demon Slayer.
Maintaining the Total Concentration Breathing state at all times is extremely difficult and taxing on the body. It requires vigorous training to master this form by expanding one's lungs and making them strong enough to perform the breathing technique around the clock. 
Total Concentration Breathing is primarily used to improve the user's stamina and strength. As Tanjiro's father explained, using the proper way to breathe can allow someone to dance forever even when it's cold outside.
While injured, taking deep breaths can be detrimental. To compensate, Tanjiro learned to use shallow breaths to reinforce the muscles around his injuries.  He's also used Total Concentration breathing to momentarily enhance his strength so he could successfully launch someone over a tree. 
Zenitsu used the breathing technique to slow down a Spider Demon's poison long enough to be rescued. 
Demon Slayers utilize the breathing technique in their swordsmanship to slay demons.
It took two years of training before Tanjiro mastered his breathing forms. This heightened his keen sense of smell and allowed him to detect the "Opening Thread". The opening thread connects Tanjiro's blade and the openings in his opponent's defense. The thread goes taut and draws Tanjiro's sword with great force, slashing the opening in an instant.
By utilizing the opening thread, Tanjiro can demonstrate water-breathing forms that enhance his attacks with powerful waves of water. There are several other different elemental variations in breathing forms as well.
- ↑ Demon Slayer: Kimetsu no Yaiba Manga and Anime: Chapter 5 and Episode 3.
- ↑ Demon Slayer: Kimetsu no Yaiba Manga and Anime: Chapter 51 (p. 2) and Episode 25.
- ↑ Demon Slayer: Kimetsu no Yaiba Manga and Anime: Chapter 24 and Episode 13.
- ↑ Demon Slayer: Kimetsu no Yaiba Manga and Anime: Chapter 30 and Episode 16.
- ↑ Demon Slayer: Kimetsu no Yaiba Manga and Anime: Chapter 34 and Episode 17.
- ↑ Demon Slayer: Kimetsu no Yaiba Manga and Anime: Chapter 6 and Episode 4.
- ↑ Demon Slayer: Kimetsu no Yaiba Manga and Anime: Chapter 7 and Episode 4.
|Total Concentration Breathing|
|Water Breathing||1st • 2nd • 2nd (Kai) • 3rd • 4th • 5th • 6th • 6th + 3rd • 7th • 8th • 9th • 10th • 11th|
|Thunder Breathing||1st • 1st (x6)|
|Beast Breathing||1st • 3rd • 7th|