In the distant future, humanity freely traverses the stars and has even developed a way to transfer consciousness into mechanized bodies, a path some believe can grant eternal life. Yet the process remains costly, and rumors persist that the prize lies at the last stop of the Galaxy Express 999, a legendary intergalactic train propelled by a locomotive reminiscent of Earth’s JNR Class C62. Twelve-year-old street urchin Tetsurô Hoshino Masako Nozawa dreams of reaching that final destination, hoping to barter a machine body for his own survival and revenge.
Tetsurô’s plan begins in Megalopolis City, where the 999 makes its yearly Earth stop. He tries to grab a pass with help from friends, only to be chased by mechanical police and lose a scarab-like locket in the scramble. On the run, he meets a mysterious woman who bears a striking resemblance to his late mother, Maetel Masako Ikeda. She claims possession of his locket and later appears on a balcony, saving him as the police close in. In his dream, she peers into his memories and watches a young Tetsurô lose his mother to the villainous Count Mecha Hidekatsu Shibata, a hunter who targets people for trophies. When Tetsurô awakens, the woman is gone, leaving only the sense that she is connected to his past and his future.
Maetel offers him passage aboard the Galaxy Express 999 on one condition: they travel together. With a sense of fate guiding him, Tetsurô agrees, returns his locket, and together they narrowly evade pursuit, boarding the train that will carry them toward the Andromeda Galaxy. The Conductor Kaneta Kimotsuki announces the first stop: Saturn’s moon Titan, a world terraformed into a hospitable oasis with a long layover. The moment they arrive, violence erupts: a man is murdered in broad daylight, and Maetel is kidnapped by the Grape Valley Bandits. Tetsurô is knocked out and wakes in the home of an elderly woman who once saved him. She reveals Titan’s “paradise law,” anarchy where people do as they please, and that Maetel’s captors are after her.
From the old woman, Tetsurô gains tools and guidance—her son Tochiro Ōyama’s Kei Tomiyama clothes and gun, a gift that connects past and present. Determined, he seeks Maetel with renewed resolve. He encounters Antares, leader of the bandits, who senses the boy’s mission and the gun’s power against mechanized foes. Antares, moved by the orphaned children he protects in the wake of Count Mecha’s violence, gives Tetsurô a path forward and advises caution, noting that a future encounter with Count Mecha will test him to the core. The two part, and the journey continues.
Pluto exposes a starkly different side of mechanization: the biomechanical dead are preserved in ice, their humanity frozen away. There, Tetsurô meets Shadow [Toshiko Fujita], a machine woman who guards the icy graves and harbors her own poignant yearning for a human past. Shadow’s beauty is tempered by a palpable sorrow, and Maetel gently rebukes her for choosing between lifespans and souls. In turn, they meet Claire [Yoko Asagami], a glass-bodied waitress who shares a quiet, hopeful dream of reclaiming her former self.
As the 999 glides on, the Queen Emeraldas [Reiko Tajima] sails the cosmos in her own ship, and Emeraldas’s presence signals a larger network of friends and rivals who orbit Maetel and Tetsurô’s fates. They arrive at Trader’s Fork, a dusty Old West-style outpost, where a luminescent machine woman named Ryuzu [Noriko Ohara] performs for a tearful crowd and a somber bartender lends his aid. The townsfolk’s warmth contrasts with the danger looming from Count Mecha’s legions, and Tetsurô learns that the path ahead is perilous and personal.
The trail leads to Tochiro’s old memory-filled ship and the mountain fortress of Mt. Gun Frontier, where Tochiro’s ghostly influence lingers. Tochiro’s end comes as he helps prepare a final confrontation with Count Mecha, transferring his consciousness into the Arcadia, the ship commanded by Captain Harlock [Makio Inoue], a legendary figure who has long served as Tetsurô’s unseen mentor. The moment of death for Tochiro catalyzes a vow in Tetsurô: revenge is not enough—he must choose humanity over mechanization and prevent others from losing themselves to the machine.
A perilous chase culminates at the Time Castle, a looming fortress that traverses space and time. Inside, Count Mecha’s forces fight to advance their era, while Antares sacrifices himself to buy Tetsurô more time. The battle peaks as Tetsurô shoots Count Mecha in the head, shattering the plan to twist time into a weapon. Ryuzu’s betrayal reveals a humanity deeper than the machine’s cold logic; Count Mecha’s empire falters as his ally’s choices pull him away from the path of tyranny. Yet the time-ravaged castle begins to crumble, and Ryuzu dies as her human warmth rusts away.
With Count Mecha defeated, Harlock arrives to rescue Tetsurô and Maetel, reminding him of the value of companionship and courage. The pair continue toward Earth aboard the 999, their bond strengthened by shared trials and the fragile truth of Maetel’s identity. Tetsurô, now weary of vengeance and eager for a chance at a life he can call his own, admits that the real prize lies not in a machine body but in preserving what makes him human. He asks Maetel to consider a future together upon their return to Earth, yet Maetel hints at the truth that her own being is bound to life across time and space—she may not be the same person the boy has come to know.
As the final stop nears, a revelation unfolds: the mechanized world of Andromeda houses its own dangerous temptations, and Maetel herself is entangled in a cycle of cloning and healing, a choice she makes to protect others from suffering. The two depart Earth once more aboard the 999, with Maetel contemplating the distance between friend and lover, and with Tetsurô clutching the memory of Tochiro’s sacrifice and the resolve to resist the lure of a machine life. The galaxy’s vastness closes behind them as the train hums onward, toward a future where humanity’s heart remains the most precious cargo of all.
