In his laboratory, biotechnology expert Dr. Kochin gathers the dragon balls intending to free his master Dr. Uirou, a mad scientist hellbent on ruling the world, forever frozen in the never-melting ice of the Tsurumai-Tsuburi Mountains. Attempting to locate the dragon balls, Gohan Son and Oolong arrive at the scene and are ambushed by several creatures known as Bio-Men. Training nearby, Piccolo attempts to save them but is then attacked by three mysterious warriors. When the ice beneath them breaks, it cuts their altercation short, burying Gohan and Oolong within. After regaining consciousness, they return home to Kame House only to encounter Bio-Men, demanding Muten-Roushi to follow them. Refusing, he easily defeats the creatures, piquing Dr. Kochin's interest. Under the impression of Muten-Roushi being the strongest man in the world, Dr. Kochin takes Bulma hostage, forcing Roushi's agreement to accompany him in mysterious plans involving his master. Who are Dr. Kochin and Dr. Uirou? What even is their purpose?

Asta and Yuno were abandoned at the same church on the same day. Raised together as children, they came to know of the Wizard King—a title given to the strongest mage in the kingdom—and promised that they would compete against each other for the position of the next Wizard King. However, as they grew up, the stark difference between them became evident. While Yuno is able to wield magic with amazing power and control, Asta cannot use magic at all and desperately tries to awaken his powers by training physically. When they reach the age of 15, Yuno is bestowed a spectacular Grimoire with a four-leaf clover, while Asta receives nothing. However, soon after, Yuno is attacked by a person named Lebuty, whose main purpose is to obtain Yuno's Grimoire. Asta tries to fight Lebuty, but he is outmatched. Though without hope and on the brink of defeat, he finds the strength to continue when he hears Yuno's voice. Unleashing his inner emotions in a rage, Asta receives a five-leaf clover Grimoire, a Black Clover giving him enough power to defeat Lebuty. A few days later, the two friends head out into the world, both seeking the same goal—to become the Wizard King!

After a janitorial mishap, an unsuspecting custodian transforms into Janemba, a fat, yellow demon who wreaks havoc throughout the afterlife. Gokuu Son has been competing in martial arts tournaments for the undead since his heroic death in the battle against Cell. Soon, Janemba's chaos draws Gokuu and fellow combatant Pikkon toward him, forcing the pair to figure out a way to defeat the giant monster. After a bout with him, Gokuu witnesses Janemba undergo another transformation: the demon sheds his fat and changes color, turning into a sword-wielding enemy more powerful than anyone Gokuu has faced thus far. With the aid of his similarly deceased rival Vegeta, Gokuu must stop the terrifying Janemba from disrupting the very fabric of the universe.

Gohan Son and Piccolo are peacefully playing when they sense a powerful entity approaching Earth. It soon reaches everyone's ears that this entity is in fact a small planet on a deadly collision course with Earth. Gokuu Son and Kuririn attempt to change the small planet's path with a Kamehameha, but the attack fails and the two warriors are blown away. However, after coming very close to Earth's surface, the object changes direction on its own and explodes soon after. The small planet reveals itself to be a vehicle for what seems to be a castle. A large army emerges out of the structure and declares that the planet is now in possession of Slug, king of the universe. While defending the city against the invaders' attack, Gohan loses his Dragon Ball, allowing Slug to take it. After reading Bulma's mind and stealing her Dragon Radar, Slug commands his army to collect the wish-granting relics. With the Dragon Balls in his possession, he uses them to wish his youth back. Now young, wise, and very powerful, Slug commences world domination.