Who Is Yoriichi Tsugikuni? The Sun Breathing Swordsman Explained
14 October 2026 · 6 min read · by OCpit
Yoriichi Tsugikuni is the creator of Sun Breathing and the strongest swordsman Demon Slayer ever shows. He was the younger twin of Michikatsu, who became Kokushibo, and centuries before Tanjiro he came closer than anyone to killing Muzan.
Who is Yoriichi?
- ▹Era: the Sengoku period, hundreds of years before the main story.
- ▹Family: younger twin of Michikatsu Tsugikuni (Kokushibo).
- ▹Breathing style: Sun Breathing, the original style.
- ▹Voice: Kazuhiko Inoue (Japanese), Mick Lauer (English).
Yoriichi was born with a Demon Slayer Mark already on his body, which gave him extraordinary perception and strength. Everyone else in the series has to awaken the Mark in battle, and it burns through their lifespan. Yoriichi is the exception who lived into old age.
The twins
Twins were considered bad luck, and the marked younger brother was the one his father wanted rid of. Then Yoriichi picked up a practice sword for the first time and beat a trained instructor without effort. He left home as a child. Michikatsu, who had pitied him, spent the rest of his life envying him instead. That envy is the whole of Kokushibo's story.
Why he became a slayer
Yoriichi married and lived quietly, with no plan to fight anyone. A demon killed his wife while she was pregnant, and that is what sent him into the Demon Slayer Corps. He taught its swordsmen to breathe, and because few of them could use Sun Breathing itself, they adapted it into the styles in our breathing styles guide.
The night he nearly killed Muzan
Yoriichi cornered Muzan and carved him up so badly that the wounds never healed. Muzan only survived by escaping, and he feared Yoriichi for the rest of the story. Tamayo was with Muzan that night. Freed from his control, she was spared by Yoriichi and went on to spend centuries working against Muzan.
Failing to finish Muzan, and having a twin who had defected to become a demon, got Yoriichi banished from the Corps.
The best swordsman who ever lived still counted his life as a failure, because one demon got away.
The Kamado earrings and the Hinokami Kagura
After his banishment Yoriichi befriended Sumiyoshi Kamado, Tanjiro's ancestor, and showed his family Sun Breathing. The Kamados turned it into the Hinokami Kagura, a dance passed down every year, and Yoriichi gave Sumiyoshi his hanafuda earrings. That is why Tanjiro wears them, and why Muzan recognises them.
How Yoriichi dies
In his eighties Yoriichi met Kokushibo one last time and was as strong as ever. He was about to land the killing blow when he died of old age, standing. Kokushibo cut the body in half, and the flute Michikatsu had made for him as a child fell out of his robes. Yoriichi had kept it all his life.
Writing a Yoriichi-style OC
- ▹Power without ambition. Yoriichi never wanted to be the best. Give your OC a gift they did not ask for.
- ▹A shadow in the family. His talent made his brother a monster. Who is hurt by your OC just existing?
- ▹One failure that defines them. Not a weakness, a single moment they replay forever.
- ▹A legacy that outlives them. Earrings, a dance, a technique: something small that carries the story on.
Build one in the Demon Slayer OC creator, find your style in the Which Demon Slayer breathing style are you? quiz, or see the other Kizuki in our demons explained guide.
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Yoriichi FAQ
Is Yoriichi the strongest character in Demon Slayer?
He is the strongest swordsman the series shows. Muzan, the strongest demon, could not beat him and fled.
Is Yoriichi related to Tanjiro?
No. He was a friend of Tanjiro's ancestor Sumiyoshi Kamado, not family. His blood relatives include Kokushibo and, through him, Muichiro Tokito.
Did Yoriichi have the Demon Slayer Mark?
Yes, from birth, and unlike every other Mark bearer he lived into his eighties.
Who voices Yoriichi?
Kazuhiko Inoue in Japanese, Mick Lauer in English.
Frequently asked
›Who is Yoriichi in Demon Slayer?
Yoriichi Tsugikuni is a Sengoku-era demon slayer, the creator of Sun Breathing and the strongest swordsman in the series. He is the younger twin of Michikatsu, who became Kokushibo, Upper Moon One. Centuries before Tanjiro, he came closer than anyone to killing Muzan.
›Did Yoriichi create all the breathing styles?
He created Sun Breathing, the first breathing style. The other styles, such as Water, Flame and Moon Breathing, branched off from it because other swordsmen could not use Sun Breathing itself.
›What did Yoriichi do to Muzan?
He cornered Muzan and nearly destroyed him, leaving wounds that never healed. Muzan escaped, and fear of Yoriichi stayed with him for centuries. Yoriichi also spared Tamayo, who was freed from Muzan's control that night.
›How is Yoriichi connected to Tanjiro?
Yoriichi befriended Tanjiro's ancestor Sumiyoshi Kamado and showed his family Sun Breathing. The Kamados preserved it as the Hinokami Kagura dance, and Yoriichi gave Sumiyoshi the hanafuda earrings that Tanjiro wears.
›How did Yoriichi die?
Of old age, mid-fight. In his eighties he faced his brother Kokushibo and was about to land the killing blow when his life simply ran out. He died standing.
›Who voices Yoriichi?
Kazuhiko Inoue in Japanese and Mick Lauer in the English dub.