Sasaki Kojiro tells the story of the genius who staked his love, glory, and life on a duel with the supreme master of the sword, Miyamoto Musashi (Tatsuya Nakadai). Oscar winning Hiroshi Inagaki directs this epic motion picture based on Genzo Murakami’s fascinating story. Despite his humble birth, the orphan Sasaki Kojiro (Onoe Kikunosuke) is determined to become the foremost swordsman in all Japan, a title that traditionally belongs to a nobleman. At fencing school, young Kojiro receives the contempt of his classmates because of his superior swordsmanship. When rumors of the upcoming civil war between Toyotomi and Tokugawa clans spread, Kojiro leaves the school and sets out, seizing every opportunity to realize his dream.

Hakuo Gakuin used to be a prestigious high school, and famous for martial arts. However, because its rival school; Seishikan, has been cowardly luring it's superior students, Hakuo was going to decline.

In the 16th Year of Keityo (1611), the lord of Ogura Castle in Kyushu admitted Sasaki Kojiro's because of his great sword techniques. However, a group within the feudal clan which supported to use guns considered Kojiro an obstacle in their goals and has the well-known ronin, Miyamoto Musashi, fight him. Now because of political gain and greed, two honorable men are to fight to the death on Ganryu Island.