"Be Forever Yamato" is a 1980 anime film that serves as a sequel to the original "Space Battleship Yamato" series. The story is set in the year 2201, three years after the Yamato's successful mission to save Earth from the Gamilas threat. The Earth Defense Force has since been disbanded, and the Yamato has been decommissioned, with its crew scattered across various roles. However, a new crisis emerges when the Black Nebula Empire, a powerful and enigmatic alien force, launches an attack on Earth. The Black Nebula Empire deploys a devastating weapon known as the Dimensional Wave-Motion Gun, capable of annihilating entire planets, and Earth is left defenseless.

Captain Juzo Okita, now gravely ill, is called back into service to lead the Yamato once more. Susumu Kodai, the former helmsman, is reluctantly drawn back into the fray, reuniting with his former crewmates, including Yuki Mori, Shiro Sanada, and Daisuke Shima. The Yamato is retrofitted with advanced technology, including a new Wave-Motion Engine, to confront the Black Nebula Empire. The crew embarks on a perilous journey to the Black Nebula, a region of space where time and space are distorted, to destroy the Dimensional Wave-Motion Gun and prevent Earth's destruction.

The narrative explores themes of sacrifice, loyalty, and the resilience of humanity in the face of overwhelming odds. The crew faces numerous challenges, including internal conflicts, the psychological toll of their mission, and the moral dilemmas of warfare. The Black Nebula Empire is depicted as a formidable adversary, with its leader, Emperor Zworder, embodying ruthless ambition and a disdain for humanity. The film builds tension through its depiction of the Yamato's desperate struggle against time and the Empire's relentless attacks.

Key characters are further developed, particularly Kodai, who grapples with his sense of duty and the personal cost of his actions. Yuki Mori's role as a bridge officer and her relationship with Kodai add emotional depth to the story. The film also introduces new characters, such as the enigmatic Teresa, who plays a pivotal role in the resolution of the conflict. The climax involves a high-stakes battle within the Black Nebula, culminating in a dramatic confrontation that tests the limits of the Yamato and its crew.

"Be Forever Yamato" is notable for its intricate plot, blending space opera with philosophical undertones, and its focus on the human element amidst interstellar conflict. The film expands on the lore of the "Space Battleship Yamato" universe while maintaining the core themes of hope and perseverance that define the series.