Highschool DxD: Crawling x Chaos - Chapter 3: New Normal

Forge unparalleled mechs with the ambition of old age, and use the galaxy as a knife to smash the edge of the empire.

His name is Ji Xinghe. When he was 65 years old, he went to Alien Battlefield to avenge his son.

The old man is standing on the ground, his ambition is a thousand miles away, the old man wears armor, and fights to the galaxy, the old man drags his sword, it is not for glory.

- Description from novelbuddy

Liola—the best assassin in his world—has vowed to kill no more. He was being chased by an assassination organization when he accidentally dropped into a parallel universe: through a dimensional gate and into poor teenager Kaiser’s apartment. Instead of going to the government shelter for lost dimensional travelers, Liola and Kaiser wind up going to school together.

Liola has been trying his best to live the life of an ordinary person, but after certain things happen one after the other, he begins to realize that being an ordinary person could be harder than being an assassin.

"What you do in life, Echoes in Eternity."

The System, who goes by the code name, Thirteen, defied the System God in order to give his previous Hosts’ the chance to change their Fates.

Unfortunately, he was killed by his Father, the System God, and was sent to the world of Pangea to struggle like the Cannon Fodders that he fought so hard to protect.

Armed with his knowledge as a System, Thirteen vowed to change not only his Fate, but the Fate of others whose destinies were tied up with him.

In a world torn by power and corruption, a fallen System will bring out a symphony of change, or lead it to its destruction.

Gods and demons fought, the worlds collapsed, only eternal immortal realm, lasting in the world.

After eternity, a god of war named Zhao Yun condensed the heavens and the earth, recast the cosmos, from the blue to the earth, marked the eternal immortal realm, in the name of the god, the king is over the world.

Since then, what he said is a myth.

- Description from MTL