The night before Planet Vegeta’s destruction, Age 737.
In a birthing pod, Lin Yu looks at the two babies next door. One has a power level of 2 and a label reading “Kakarot, sent to Earth.” The other has a power level of 10,000, and Frieza’s soldiers have covered his pod with “high risk” warnings.
As his pod, number 777, is wheeled toward the launch platform, a mechanical voice suddenly rings out in his mind:
[Binding successful! Targets: Son Goku and Broly.]
[Rules: Each time a target gains 1 point of power, you receive 10,000 times that amount. When a target learns a skill, you receive an optimized version.]
And so...
When Son Goku falls off a cliff on Earth, his power rises by 10, and 100,000 points of power surge through Lin Yu;
When Broly rips apart an ice-age beast on Planet Vampa, his power rises by 5,000, and Lin Yu’s ki alone shatters the mountain ranges on Planet X-99;
And when Goku transforms into a Super Saiyan for the first time, Lin Yu watches his power level shoot up to “1.5 trillion” and silently crushes the energy ore in his hand.
Later, Raditz arrives on Earth, and his Scouter shrieks before exploding: “Three power levels over 10,000 detected... Wait! The power level of that guy named Lin Yu can’t be measured!”
Frieza roars on Planet Namek: “Why does that Saiyan who appeared out of nowhere get stronger every time Son Goku does?!”
Beerus scratches his cat-like ear. “That number 777 has steadier ki than a God of Destruction... Who is he, exactly?”
Leaning against a vein of energy ore, Lin Yu looks at the names on his System screen: “Son Goku (Super Saiyan Third Grade)” and “Broly (Legendary Super Saiyan, berserk).” He casually flicks away an incoming meteorite:
Don't go too far, the Ambassador of the Mythical King and the King of All