Breath of the Sun

The Breath of the Sun (の) is an as-of-yet-unseen style of swordsmanship. It was utilized by the first Demon Slayer, Yoriichi Tsugikuni, and serves as the basis for other Breath Styles derived from it due to him changing the breathing techniques to suit the individuals he taught, that eventually branched out into the Breath of Flames, Breath of Water, Breath of Wind, Breath of Stone, and Breath of Thunder, which branched out into even more breath styles themselves. Before Kokushibo died, he mentions that all users of the Breath of the Sun were killed by him and Kibutsuji Muzan, before proceeding to question why the Dance of the Fire God exists due to its presumable similarity to the Breath of the Sun's techniques.

Trivia

 * The kanji,, for "Sun", has the same pronunciation as the kanji , which means "Fire".