When four pilgrims arrive in Edo following a star, their tidings of a newborn priest enrage Emperor Makoto Shishio who will tolerate no threat to his iron rule. The strongest swordsman in Japan, now father of the prophesied child, must fight to protect his wife and baby from the emperor's power with the four pilgrims as his allies.

It is the Menji era and the hitokiri Battousai is slaughtering Christians by the hundreds. Until one day after an assassination assignment, he encounters the truth of what he has done.