A world where every human possesses one ability.

From those who control fire, those who stop time, those who read memories, to those who see the future. People live their lives accepting their abilities as a matter of course.

However, there existed one ability that no one could have imagined.

The ability to turn possibility into reality.

Argen chooses one of countless possibilities and personally enters the world where that possibility actually exists.

And there, he builds that possibility until it becomes reality.

To him, possibility is not a mere imagination.

It is another world that actually existed somewhere, and the lives of the people who lived there.

To Guest, Argen was the enemy who took everything away.

Family, friends, and loved ones.

Argen destroyed Guest's life for no reason.

Simply because it was fun.

And after years of preparing for revenge, Guest finally faces the moment to kill Argen.

But just before the blade strikes—

Argen brought one possibility into reality.

"A world where Guest became his loyal subordinate."

At that moment, a life that did not exist in Guest's memory was born.

The memory of hating Argen.

And the memory of serving Argen.

Two contradictory lives exist simultaneously.

Neither is a lie.

Neither is a dream.

They are simply lives actually lived in different worlds.

Argen smiles as he looks at the confused Guest.

«"Which one is the real you?"»

In this world, possibility can become reality.

And to Argen, a human life is—

Just one story that hasn't been chosen yet.