MTL - Urban Tales of Demons and Spirits - Chapter 2 Komura (above)

There was a mysterious old man who approached the failed swordsman with the “100 million years button”. A magic button which can achieve the same effect as training for 100 million years if you push it.

The failed swordsman who pushed the button had his doubts, but immediately felt tremendous power rising in his body. So he pushed the button many times.

However it was a cursed button. The moment it was pushed, he was confined to the 100 million years prison of time. The first 100 years were devoted solely to training. After 1000 years he had forgotten why he swung his sword. He stopped thinking completely after 10,000 years had passed. After 100 million years he became crippled and finally managed to return to the real world. At the same time losing all his memories from the past 100 million years, the only thing that remained were his sword techniques. “I can become stronger just by pressing the button!” or so he thought and pushed the button many times after that. Foolishly trapping himself in that 100 million years of hell each time.

As he continued this loop, he began to think “If I destroy this world, will I get out of here?” A few billion years later, he finally escaped from the loop.

This is the story of a failed swordsman trying to make a name for himself in the world.

Aoki’s resolute face was indifferent. “If the sun doesn’t shine on me, please let me be surrounded by darkness!”
From a different perspective, look at the entire Pokemons world.

- Description from Uukanshu

In a world of endless star fields and interdimensional wars, the wizards' floating city conquered one world after another.At the wizard academy, through blood-stained exams, the towering wizard tower sent wizards batch after batch.Becoming an apprentice wizard, Richard activated the miracle furnace deep within his soul, where constant refining of materials granted him knowledge and skills...The veteran's weapon could be refined into legendary martial arts techniques.The ancient wizard's encrypted notes could be refined into lost knowledge.The remains of brutal monsters could be refined into monster bloodlines.In this era of great voyages in the wizarding world, Richard was destined to become a leader of his time.

This legend tells the tale of the protagonist, Kuroki summoned to protect the demon king from the hero.

Kuroki, unbeknownst to him, suddenly came to another world. He was summoned by the demon king, Modes. The territory which the demon king overrules was in the midst of being destroyed because of the hero. He had no choice but to bow before Kuroki.

“Please save us, Savior Dono!”

Kuroki nodded, deciding to save the demon king due to an unexpected turn of event.