"Doraemon: Nobita's Little Star Wars 2021" is a remake of the 1985 film of the same name, part of the long-running Doraemon franchise. The story centers on Nobita, a young boy who, with the help of his robotic cat companion Doraemon, embarks on an intergalactic adventure. The narrative begins when Nobita discovers a tiny alien named Papi, who hails from the planet Pirika. Papi has fled his home due to an invasion by the militaristic Gilmore Army, which seeks to exploit Pirika's resources and subjugate its inhabitants.

Nobita and his friends—Shizuka, Gian, and Suneo—decide to assist Papi in reclaiming his planet. Using Doraemon's futuristic gadgets, they shrink themselves to Papi's size and travel to Pirika. Upon arrival, they find a world under siege, with its peaceful inhabitants struggling against the oppressive Gilmore forces. The group devises a plan to rally the Pirikans and resist the invaders, leveraging their ingenuity and Doraemon's advanced tools.

The plot explores themes of friendship, courage, and the importance of standing up against injustice. Nobita, often portrayed as timid and clumsy, demonstrates growth as he takes on a leadership role, inspiring the Pirikans to fight for their freedom. The story balances lighthearted moments with action-packed sequences, as the group faces off against the Gilmore Army's formidable technology and weaponry.

Key characters include Nobita, whose determination drives the mission; Doraemon, whose gadgets provide crucial support; and Papi, whose plight serves as the emotional core of the story. The Gilmore Army, led by the ruthless Commander Gilmore, serves as the primary antagonist, embodying the threat of unchecked militarism and exploitation. The narrative culminates in a climactic battle where the combined efforts of Nobita, his friends, and the Pirikans lead to a resolution that underscores the power of unity and resilience.