Dr. Stone › Saison 1 Dr. Stone : Stone World

Chapter 4 — Episode 4

First, the episode opens with Senku privately acknowledging that Tsukasa is a good person — but also a killer — framing their situation as a race: if Senku completes a science weapon before Tsukasa notices, they win; if discovered first, they lose. Meanwhile, Taiju shares a tender moment with Yuzuriha, telling her he has waited 3,700 years to finish a confession he started before the petrification, and that he will only say it once civilization is fully restored. Then, Senku reveals he has gathered all three ingredients for gunpowder — sulfur from hot springs, charcoal from burned wood, and potassium nitrate from the miracle cave — and begins the "gunpowder cooking" process. During the mixing and compacting phase, Taiju accidentally triggers an explosion by striking the mixture, sending the group flying. The blast smoke, however, is spotted in the distance, suggesting other humans may be living in the Stone World. Senku faces a dilemma: extinguish the fire to stay hidden from Tsukasa, or send up a signal flare to contact the unknown survivors. He chooses to light more signal fires, accepting the risk. Finally, a flashback reveals Senku's childhood passion for science and his dream of reaching space. Back in the present, Tsukasa confronts Senku directly, demanding he swear to abandon science forever. Senku refuses, and Tsukasa — after a brief, almost regretful exchange about what could have been if they had met before the petrification — strikes Senku with a lethal blow to the neck, leaving him apparently dead as the episode ends on a cliffhanger.