Yoriichi Tsugikuni is a legendary figure in Demon Slayer—the strongest swordsman of the Sengoku Period and the originator of Breathing techniques. He was born with the penetrating insight of the Transparent World, and at the age of seven he grasped Sun Breathing, the source from which all later Breathing styles would descend. He once single-handedly struck down Muzan Kibutsuji, driving him to the brink of death and leaving wounds that would never heal. Sun Breathing branched through him into countless Breathing schools, and the sun-patterned hanafuda earrings he wore were passed down through the Kamado family together with the Breathing techniques, becoming a crucial inheritance for later generations in their fight against Muzan. Yet this power, so far ahead of its time, also brought him profound misfortune. His elder brother, consumed by jealousy, became a demon, and his wife and child were cruelly slain. Having lost everything, Yoriichi spent the remainder of his life in long wandering and self-exile—his very existence an embodiment of the loneliness and sacrifice of one who transcends his era. As the pinnacle of both combat ability and spiritual attainment in the series, he is at once the origin of the Demon Slayer Corps' conviction and the insurmountable, eternal legend of the world of Demon Slayer.
Those who walk their path to the very end shall arrive at the same destination.