The following contains spoilers from the Demon Slayer: Kimetsu no Yaiba manga, available now in English via Viz Media.
In Demon Slayer, the Hinokami Kagura is a dance ritual that Tanjiro learned from his father. Each year, the Kamado family performed the ceremony as an offering to the Fire God for protection from death and illness. As a kid, Tanjiro watched his father dance all night, even in the most bitter winters.
After learning the dance, Tanjiro utilized it in combat against demons. Not much is known about his father, Tanjuro, and how he learned the Hinokami Kagura. Although the dance is passed down through the Kamado family, a theory involving reincarnation suggests that Tanjuro learned the technique through other means.
Reincarnation in Demon Slayer
A major concept in Demon Slayer is the idea of reincarnation, which is evident in the manga's finale. Many of the beloved characters passed away during the final battle against Muzan. Tanjiro and his close friends who survived went on to have families together. The finale fast-forwards to the 21st century, focusing on the descendants of Tanjiro, Zenitsu and Inosuke and how life is without the threat of demons.
As Tanjiro's descendant, Sumihiko, goes to school, many of the deceased demon slayers appear in passing. For example, Iguro and Mitsuri are married and run a restaurant together. Sanemi's descendant works as a police officer and is close to a young male who appears to be the reincarnated version of Genya. Muichiro and his twin brother even make an appearance as babies. Those who passed away seem to have come back to life and share similarities with their former selves, even though they appear to have no recollection of their former lives.
Who Is Tanjuro a Reincarnation of?
The reincarnation theory suggests that Tanjuro is a reincarnation of a former demon slayer -- specifically, Yoriichi Tsuginkui. Yoriichi was regarded as the strongest demon slayer and the inventor of sun breathing. Sun breathing is the first breathing technique that all subsequent forms are based on. It is also known as the Hinokami Kagura Dance, which has been passed through the Kamado family for generations.
It is important to note that the Kamado family isn't related to Yoriichi. Tanjiro's descendant, Sumiyoshi Kamado, was a close friend of Yoriichi. By watching Yoriichi train, Sumiyoshi learned and memorized the movements of sun breathing, which he then turned into a dance. After Yoriichi passed away, Sumiyoshi promised to keep his legacy alive by passing the Hinokami Kagura and Yoriichi's hanafuda earrings to each son within his family.
The Similarities Between Tanjuro and Yoriichi
Yoriichi wanted to live a quiet, peaceful life with his wife and start a family. He was a calm and reserved man who originally quit being a demon slayer due to his dislike for violence. Despite his strength and vast accolades, Yoriichi was humble and didn't view himself as special or god-like. He shared many personality traits and similar physical characteristics to Tanjuro.
Tanjuro achieved everything that Yoriichi wanted, having a large family with his wife. He led a simple life and used the Hinokami Kagura as a form of art and ritual rather than a sword technique that could harm others. Additionally, Tanjuro could enter the Selfless State, which Akaza referred to as the highest state of physical combat that one can achieve. The only other individuals to accomplish this feat were Tanjiro and Yoriichi himself. It's possible that after his passing, Yoriichi had a second chance at life. With his reincarnation, he could live the life he truly wanted and be an inspiration to Tanjiro, who managed to achieve the one thing the former failed to do before his passing: defeat Muzan.