Son of the Hero King - Chapter 659:

The prosperity is about to come to an end, and the poor boy quietly rises.

Traveling across time and space, seek the leader of the world.

- Description from novelbuddy

A continuation from where High School DxD Volume 25 left off.

Mr. Tycoon Is Actually the Father of My Child!

Hyde arrives in a doomed world with nothing but his body and fragmented knowledge of the future from a game he once played. He has no grand ambition—why try to save a world already destined to fall? Survival is enough.That is, until he discovers his sister is also transported into that world.However, only he hears the Melody of Nightingale and receives the power to survive.[You have established a connection with The Forgotten Hollow.]Awakening as a Resonant—an elite group with supernatural abilities—he is thrust into a conflict between two worlds. Armed with the authority of space and time, he vows to protect his powerless sister at all cost, even if he has to fight against the Mirage creatures, other Resonants, or even Gods themselves.