Jikuu Mahou de Isekai to Chikyuu wo Ittarikitari - Chapter 303 – Police Interrogation

He Lang died by his own hands for the sake of his imperial younger brother’s ambition, whom he loved. He was offered to be reborn in exchange for giving up his past romantic feelings. Reborn without the burden of his romantic feelings, he brings with him a manual to new worlds. He wholeheartedly followed the instructions of the manual to complete the tasks, not knowing that the originally slag gong was blackening…
He pleaded to his affectionate Emperor brother to release him, he pleaded to the paranoid prisoner next door, but until the end he remained baffled.
In the end, he discovered that the full name of the manual was – “Slag Shou Cultivating Manual”
Σ (っ ° ° °;) っ!

- Description from Novelupdates

A young middle school student faces a life-altering choice. Destined for mediocrity and without a War Spiritual Bloodline, he dreams of transcending his ordinary existence and becoming a high-status War Spiritualist. His world is transformed when he becomes bound to the “”Godly Pet Evolution System,”” enabling him to activate his War Spiritual Bloodline and cultivate divine pets, even from the most unlikely sources.Armed with this system, he defies expectations by nurturing underdog spirits into formidable allies. The seemingly weak flower spirit evolves under his care, as does his Lord White Dragon, challenging the mightiest thunder-attribute battle spirits. Even when presented with a Diamond Demonic Spirit Card, he counters with three Epic-Demon Spirit Cards of his own.His journey takes an unexpected turn as powerful entities, including the Six-Tailed Demon Fox, the Phoenix Holy Maiden, and the Queen of the Seas, vie to become his second battle spirit. Faced with a wealth of choices, he refuses to settle for just one and ambitiously aims to harness them all.

This novel is also known as Random Skills: Exploring Dungeons

Legend has it that this world has magical qualities

Attract fragments of the broken world to strengthen yourself

It could be a building, an area, or a piece of history

These cages called earth in this world are dungeons

Wealth, power, power, everything can be found in endless dungeons to explore.

Life, emotion, freedom, everything is the price to pay for exploring the dungeon.

Kane looked at the Book of Adventure that was in front of him.

Opened it and looked, this is not the game system.

He knew he was about to take off.

- Description from novelbuddy

In a monstrous post-apocalyptic setting, this is a story of how a lowly Inventor, Lance, conquered a nation governed by immoral group of Scientists called The Corporation. He grew and climbed up to the highest rank possible as a Scientist with his inventions and side businesses. Eventually, he became a weapons inventor, building weapons to two opposing sides. In doing so, Lance always crossed a dilemma. How could a nobody topple the most powerful government? How could one overcome circumstances beyond his grasp, especially in a world filled with monstrous mutations called the Abominants?