Mirai Trunks has restored peace to his world by defeating 17,18,and Cell.
Trunks was training very intensely under 900x's gravity and all of a sudden he sensed an evil attacking the dashed off towards the found the city in ruins.
Trunks saw a giant fox that had orange fur and nine tails that were lashing out at the surroundings.
Buildings crumbled and earthquakes were fox then fox then fired condensed balls of chakra at its were occuring had seen enough.
Trunks then yelled"HAAAAAAAAA!" Trunks transformed into a super saiyan.
His eyes truned turquoise and his hair turned golden and became spiky.
Trunks was engulfed in golden dashed at the beast and punched it in its face knocking it into a nearby saw the beast get beast looked around to see Trunks.
Then fired many balls of condensed chakra from its mouth at deflected all of them.
The fox said"Damn you! You Dare Mock ME?" Trunks said"No but you have no right to do 've killed thousands of innocent people and they have done nothing to you."
Trunks said"I'm giving you one chance now leave and never return."
The giant fox laughed"HAHAHA! You are letting me the great Kyuubi recieve mercy? DIE!"
Kyuubi jumped at Trunks and slashed at him using its then recieved large cuts across his powered up and dashed at fired giant fireball from its mouth at him.
Trunks continued flying in the same then kicked the fireball out of the atmosphere.
Trunks then sensed a rise in Kyuubi's energy level it higher than Cell's now.
Kyuubi gathered chakra the center of its raised it's chakra and a red flamelike aura surrounded Kyuubi.
Kyuubi finished powering up then fired a condensed energy beam at Trunks.
Trunks thought"That blast will destory the planet 10x's over.I won't allow it."
Trunks powered up and yelled"Final Buster Cannon!" he fired a powerful green beam.
Their energy blasts collided and the ground began to put more power into its blast.
Kyuubi's attack almost completely overpowered Trunks' yelled"HAAAAAAAAA!"
Trunks powered up to his maximum power and charged his attack with more power.
He completely overwhelmed Kyuubi annihilating the fox.
Trunks said"Now time for some rest." A few weeks later Trunks helped rebuild and restore life on on he continued training knowing that a new threatening to destroy earth might come at anytime.
Trunks remebered an oath he took when Gohan died."I sware to do eevrything in my power to protect the earth.
Even if it kills me I will never let anyone or anything ever get away with causing harm to earth."
Trunks remebered those words by continued living in peace for a time.