Igarashi | Natsu

When Senku and the team arrive, they do not mock this facade. Instead, they validate it. Senku, in his typical pragmatic fashion, uses Natsu’s local knowledge and his emotional connection to the rocket as a tool for their mission. But in doing so, Senku inadvertently offers Natsu the greatest gift: purpose. By helping to repair the real Soyuz and plan the journey to the moon, Natsu is given the chance to turn his childhood play-acting into genuine heroism. He moves from being a boy waiting for his parents to return to a young man building the vehicle that will bring them back—or finally confirm their fate. One of Natsu’s most critical functions in the narrative is as a keeper of oral history. In a world where books have turned to dust, the memory of the old world is fragile. Natsu, raised on stories of the astronauts and the petrification event, represents the human chain of memory. He is the living link between the era of spaceflight (Byakuya, Lillian, Shamil) and the era of reconstruction (Senku, Chrome).

He also serves as a foil to the series’ antagonists. Unlike Tsukasa, who sees the old world as corrupt, or Ibara, who sees only power, Natsu sees a continuous line of human value. The past (his parents, the astronauts) is sacred. The present (his friends, his village) is precious. The future (the moon mission) is hopeful. He reconciles these three tenses of time through the simple, radical act of caring. igarashi natsu

His introduction is steeped in tragedy. He lives in the shadow of the “Why-Man” mystery, believing that his mother, Kohaku, and the other astronauts left for the moon and never returned. The persona he adopts—that of the “commander” Soyuz—is a poignant act of childhood faith, a desperate attempt to hold onto a narrative where his parents are heroes on a mission, not casualties of an impossible voyage. This foundational trauma shapes Natsu’s entire character arc. He is not motivated by a lust for discovery or a thirst for battle; he is driven by a profound need for closure and a quiet fear of abandonment. Natsu’s relationship with science is unique among the Kingdom of Science’s allies. Unlike Chrome’s manic glee or Senku’s clinical precision, Natsu treats science as a solemn ritual—a way to make sense of a world that has already taken everything from him. His role as the fake “commander” of the Soyuz spacecraft is a beautiful metaphor for his internal state. He is a child playing a part, using the language of space exploration (coordinates, trajectories, command protocols) to create a protective shell of order around the chaos of his emotions. When Senku and the team arrive, they do not mock this facade

This is a crucial narrative lesson. Senku’s courage is born of certainty and knowledge. Kohaku’s courage is born of physical prowess and instinct. Natsu’s courage is born of love . He fights not because he knows he will win, but because he cannot bear to live in a world where he did not try to save his family. His decision to board the Soyuz capsule during the final launch preparations—not as a commander, but as a son sending his parents a message—is one of the most quietly heroic moments in the series. He proves that emotional strength is as vital as physical or intellectual strength. By the end of the series, Igarashi Natsu does not become a famous scientist or a legendary warrior. He remains a farmer, a guardian, and a man of deep feeling. But his role is foundational. He represents the purpose of the Kingdom of Science. All of Senku’s rockets and revival fluids are ultimately meaningless if there is no one to care about the people being saved. Natsu is the emotional core that prevents the series from becoming a cold, procedural textbook. But in doing so, Senku inadvertently offers Natsu