Keizo

Keizo was a kind, upbeat man who used his strength to shield others. His optimism and empathy ran deep enough to take in Hakuji, a former convict, teaching him the Soryu style, trusting him with his sickly daughter, and ultimately welcoming him into the family as Koyuki's husband and the dojo's next head.

His words and example left a lasting mark on Hakuji, surviving even the demon's transformation and lost memories. Meeting Tanjiro, who shared Keizo's righteous outlook, stirred those buried lessons back to the surface.

After rescuing a man from bandits, Keizo received the land for his dojo as thanks. He took a wife and fathered Koyuki, a frequently sickly girl, and the strain of her care eventually drove his wife to take her own life. Lacking students, he took odd jobs to support them.

While traveling, Keizo was asked to deal with a violent banished youth named Hakuji. After knocking him out, he saw promise in the boy and took him in, offering training and shelter in return for caring for Koyuki. When her health improved around her sixteenth year, he offered Hakuji the dojo and Koyuki's hand. While Hakuji visited his father's grave, a vengeful rival poisoned the well, and Keizo and Koyuki unknowingly drank from it.

Though entirely human, Keizo was an extraordinary martial artist, able to defeat a band of bandits by himself and knock the formidable Hakuji unconscious with a flurry of swift punches. He was also a fine teacher, passing on the Soryu style that Hakuji would later twist into the foundation of his demon technique, Destructive Death.

His core art, Soryu Style, was a bare-fisted fighting form he either devised or inherited from his own master. Akaza's rapid-punch technique, Disorder, plainly resembles the assault Keizo used the day they first met.