When a miniature extraterrestrial named Papi emerges from a tiny rocket in Nobita's possession, revealing himself as the president of Pirika, a planet in turmoil, Doraemon and his companions are taken aback by his size. Through bonding over the 'Small Light' gadget and playful interactions, they forge a deep friendship. However, a menacing whale-shaped battleship descends to Earth with the intent to seize Papi, prompting a defensive stance by the newfound friends. Determined to shield their tiny ally, Papi takes a brave stand against the rebels, leading Doraemon and his pals on a daring mission to Pirika to safeguard their cherished friend and his imperiled homeland.