Kotetsu is a first-year pilot trainee at the Animal Kingdom Space Academy, a school where animal characters study to become astronauts and explore the cosmos. When a rumor reaches him that aliens have been sighted nearby, he becomes determined to investigate. Kotetsu rallies his classmates to join the search, and the group splits into teams to comb their surroundings for any sign of extraterrestrial life. As the investigation unfolds, their pursuit of the rumored aliens leads them into topics ranging from UFO sightings and lunar exploration to the mysteries of Mars and the nature of black holes. The deeper they dig, the more they realize how much about the universe remains unknown.

Kotetsu is an energetic and endlessly curious young animal who dreams of one day piloting a spacecraft. His enthusiasm often drives the group forward. Nico is the studious top of the class, offering scientific explanations with a calm and sometimes cool demeanor, though he hides a softer side. Roo is an inventor fascinated by technology, always tinkering with gadgets. Hikaru is bright and inquisitive, bringing contagious energy to every expedition. Otama is a cheerful aspiring chef whose optimism keeps the team spirits high. Kotetsu's enthusiastic grandfather, Jii-chan, and Izumi-sensei, a teacher at the academy, support the children from the sidelines, while the pun-loving School Principal oversees the institution with a fondness for wordplay. DAXA-kun, a mascot character whose name winks at Japan's real space agency JAXA, appears throughout to present fun facts and space trivia.

The story is set at the Animal Kingdom Space Academy, a whimsical school nestled in a world of talking animals who share a common goal of reaching the stars. The film blends re-edited footage from the television series with live-action space imagery sourced from NHK science programs and recordings made by JAXA, Japan's space agency. This mix of animation and real footage creates an experience that floats between fiction and documentary, inviting viewers to learn genuine astronomical facts while following the characters' lighthearted adventure. The students' investigation takes them from the academy grounds into forests and caves, and eventually into a wider consideration of the solar system, as the boundary between make-believe and actual space exploration softens. Each new location or concept they encounter—a UFO sighting, the surface of the moon, the red plains of Mars, the crushing pull of a black hole—is paired with real scientific context, turning their search into a journey of discovery about the universe itself.