Baka to Test to Shoukanjuu‎ - Volume 9, The Third Question

In the far future humanity is threatened by monstrous beings called kaiju now humans have expanded across the galaxy with the development of new techniques and fleets of mechs.Alto a young boy with dreams of becoming a great mech pilot is forced to be a mech designer. He finds a strange technology that opens his eyes to the vast secrets of the galaxy, now with a new purpose Alto must become something the world has never seen before.A/N: Just wanna do a good sci-fi book

The world had started doomsday, and I struggled for a year, before I died under an enchanted beast’s claw. Heaven has given me another chance, back a day before the end happen. Will I be able to change my fate, and that of my loved ones? Now, I will start my journey on becoming the strongest on the planet that the Gods have changed into a game world.

- Description from Novelupdates

To take a dragon's hoard is to challenge death.The greatest of the sea-drakes wakes, curled on his silver throne; but there is no silver. His hoard is stolen. He rises, screaming, and chases the thief to the ends of the world—only to be shot from the sky.But dragons do not die easy, and never one with such festering hatred. A dungeon core rises from his corpse.If he intends to survive so near the cove of pirates that slew his past self, he'll need to master his powers—and quickly. For these pirates are dragonslayers; they won't be felled by mere mushrooms or spiders.Beneath the lawless Calarata, the young dungeon core will have to fight to survive; and one day, he will return death to the man who killed him.

A little ruffian who fought recklessly without any morals and bottomline accidentally time-traveled to parallel space and became a Key Case Investigation Team agent. The huge change in identity had him creating chaos in the police station. However, a strange miracle system helped him repeatedly solve mysterious cases, turning him into an impudent ruffian detective!