During the Battle of Sekigahara in 1600, the notorious killer Demon Eyes Kyo and the noble swordsman Kyoshiro Mibu fight to a standstill just as a meteor strikes the battlefield and both vanish. Four years later, bounty hunter Yuya Shiina is tracking down Kyoshiro, now a debt-ridden medicine peddler, when a monstrous attack wakes something else inside him: Kyo's consciousness, trapped in Kyoshiro's body ever since that day. The two share one body and clashing goals as they set out to untangle what really happened at Sekigahara.