In the tumultuous year of 972 A.D. in Kyoto, a city plagued by corruption and distress, a renowned samurai named Minamoto no Raiko is tasked by the Imperial Court to retrieve a fabled gem with the power to heal the world. Stricken by illness, Raiko's courageous sister, Hikaru, undertakes the perilous quest in his stead. Along her journey, Hikaru encounters diverse characters and embarks on thrilling adventures in pursuit of the legendary gem.