300 years ago, Japan’s greatest swordsman Yagyu Jubei led his clan of samurai triumphantly against the villainous Ryujoji clan. On his deathbed, Yagyu transferred his abilities into a heart-shaped eyepatch. There will be a successor and this deserving person will receive all the power and skill of Yagyu Jubei along with the Lovely Eyepatch that transforms the wearer into an unbeatable warrior. After 300 years of searching, Koinosuke (whose aging has all but stopped) finds this successor in a perky young schoolgirl who has just moved into town named Nanohana Jiyu, who coincidentally, has been nicknamed "Jubei."