Senku's father, the astronaut Byakuya, returns to Earth shortly after humanity is turned to stone. Certain that his son will eventually survive the petrification, he leaves something behind for him to find. But will it survive the ravages of time? In the present, Senku and the villagers have to contend with attackers from the Tsukasa Empire. The dire situation calls for drastic measures, so they get to work on the strongest weapon yet-katanas!