The past, the present, the future, and fate.
They form the foundation of the world, and represent the powers of the mortal realm.
The past is eternity, representing the power of that which never changes.
The present is the era, representing the greatest power.
The future is potential, representing power that is infinitely strong, yet infinitely weak.
Chosen by the past, one becomes the Lord of the Unchanging.
Chosen by the present, one becomes the King of the Era.
Chosen by the future, one becomes the Emperor of the End and the Emperor of Hope.
Chosen by fate, one becomes the Emperor of Heaven's Mandate!
The chosen boy ultimately embarked on the path laid out by fate. If he did not want to be bound by fate, he would have to keep moving forward. If humanity could not do it, then he would become a more powerful being, until he became an ultimate existence that even the gods could not look upon.
The world is finite, but dimensions are infinite.
Fight without end, and become the ultimate being.
Become the master of fate!
The heroine is Yae Sakura (ฅω*ฅ)
World order: Akame ga Kill! → Fourth Holy Grail War → Campione! → Dragon Raja → Problem Children Are Coming from Another World, Aren't They?
[The first two volumes are a beginner's attempt. Proceed with caution.]