Kojirou Sasaki

A swordsman known for his duel at Ganryu Island with Musashi Miyamoto (voice - Toshio Mogami). His weapon is a Bizen Osafune with a length of over three feet, forged by a divine craftsman. Einherjar, those who become warriors, appear in their prime regardless of their age at death, but Kojirou has continued to refine his swordsmanship through the evolution of the Ganryu style for centuries after his death, resulting in his appearing older than when he died. He confidently claims, "This moment is Kojirou's prime."

During his lifetime, he attended the Tomita Dojo in Echizen Province and was considered a burden for oversleeping and giving up when about to lose. However, with each defeat, he pursued skills for victory, studying and training alone, possessing a talent that even his master, Tomita Seigen, who later realized Kojirou had surpassed him, recommended him as a fencing instructor for the Asakura family, which he refused. He left the Echizen domain and traveled the country, losing continuously to famous and strong swordsmen, seeking ways to surpass them alone. He never won in his life, but later, by constructing and repeatedly fighting his opponents in his mind, he continued to surpass them, earning the title "the strongest loser in history." In his fight against Musashi Miyamoto at Ganryu Island, he realized Musashi's strength and thought he couldn't win yet, continued the fight knowing it would kill him, found the battle "enjoyable," declared stopping it would be a "lifetime loss," and continued fighting Musashi until he was finally slain by him.

By crossing swords with numerous swordsmen thousands of times in his mind, he could perfectly construct an opponent in his mind based on minimal information such as breathing and walking, allowing him to experience attacking patterns beforehand, reaching a state known as "Thousand Hand Musou." Furthermore, after his bout with Poseidon, with the support of many swordsmen who had helped him grow, he was able to read even the gods' moves perfectly, developing "Myriad Hand Musou." Not only Ganryu techniques but also those of the swordsmen he fought during his life were experienced and remembered through "Thousand Hand Musou," usable in what he called "Niten Ganryu," proclaimed as unmatched by Musashi.

After his victory over Poseidon, he soaked in the thrill of his first-ever win, leaning on Frist for support as he exited the arena for treatment. However, in the tense situation triggered by Loki and the Seven Lucky Gods against Shaka, he stated that gods are no different from humans in their actions, but remarked that Poseidon wouldn't do this, and joined Shaka's side, not liking the odds. He has since been accompanying Frist, watching Ragnarok with figures like Okita and Kondo.