Hailing from planet Wan-Bau in the Animal Stellar Region, Pochi Rickman travels to Earth researching plant life for Zughan—a substance declared extinct across the universe. During this mission, he sustains injuries in a corn field and is discovered by five elementary school children searching for their missing pet rabbit. Unaware of his alien nature, they nurse him back to health.

After recovery, Pochi reveals his extraterrestrial origins and speech ability. As gratitude, he offers the children a moon sightseeing trip. This excursion strands them in space when lunar authorities impose an Earth travel sanction following reports of his earlier injury.

His role shifts from beneficiary to guide as the group voyages across the galaxy toward his homeworld, Wan, seeking an alternate path back to Earth. Though a professor on Wan, occasional lapses in responsibility initially undermine the children’s trust in his competence. His father, Taro Rickman, practices as a physician specializing in rare and complex diseases.

The group faces pursuit by agents of "The Space Show," an interstellar entertainment program hosted by antagonist Neppo. These agents caused Pochi’s initial injury during his Zughan research. Neppo seeks Zughan to power his spaceship Pet Star and achieve godhood. Since Zughan shares botanical kinship with Earth’s wasabi, and one child carries wasabi root, the group becomes Neppo’s target.

At the climax during an interstellar festival on Wan, Neppo captures both the wasabi and the youngest child, Amane, via tractor beam. Pochi participates in Amane’s rescue, collaborating with journey allies. The confrontation defeats Neppo, retrieves Amane, and preserves universal stability. Afterwards, Pochi facilitates the children’s return to Earth, ensuring their arrival precedes parental notice.