In Episode 4, Goku and his companions find themselves stranded in the Demon Realm after their aircraft is stolen. The dense air hinders their ability to fly long distances, so they set out on foot in search of a vehicle to return to Earth. Along the way, Goku uses his ability to sense Ki to detect hidden creatures and fends off these invisible attackers.

They reach a shop where they rest and are introduced to "Medi-Beetles"—insects with various healing properties, similar to Senzu Beans. Fascinated by their potential, they buy several types, including Revival Beetles, which restore stamina, and Fusion Beetles, which temporarily fuse two people together to increase their strength.

Glorio, who acts as their guide, helps them obtain a "Sky Seed," a seed from a giant demon flower that carries them through the air before crashing. With the Sky Seed, they cover a considerable distance but still have half a day's journey ahead. Goku remembers Piccolo mentioning the Demon Realm's Dragon Balls, the originals guarded by powerful warriors called Tamagamis. They decide that collecting these Dragon Balls could help them return to normal and save Dende, agreeing to change their mission.

As they travel further, they reach a town where they witness the Gendarmerie—the military police under the new Supreme Demon King Gomah—oppressing the villagers. The Gendarmerie demands exorbitant gold coins as tribute and threatens to take years of the villagers' lives if they cannot pay. An old man is targeted for failing to meet their demands, prompting a mysterious girl to intervene with a homemade "Wasabi Bomb" against the oppressors. Goku and his friends assist her, leading to a confrontation with the authorities. The episode ends with the girl recognizing Goku.