"I'm a Hero who came from another world."

"I was summoned into this world by the goddess with the goal of overthrowing the Demon King endangering the world, to let the world regain its peace."

"I am well aware that this is a great task with heavy responsibility, but since I've been summoned and became a Hero, I ought to get motivated and overthrow him (her) for good. Even if the opponent is the incomparably powerful Demon King."

"Don't ask me why, that's what's written in the book."

"However...... didn't this development deviate somewhat from the script!!!?"

This is the beginning of the fraud of crossing worlds. It is also the tale of the Hero carrying the mission of overthrowing the Demon King finally discovering in shock that he had been set up.