MTL - Seeking the Flying Sword Path - v20 Chapter 3 Not enough

He died on the wedding of the girl he had a crush on, after a long and successful career. After convincing Yama to send him back to the world, he decides to fix the areas in which his life went wrong. Realizing the lack of love and romance in his past life, he sets out to conquer the hearts of various women.

- Description from Novelupdates

A world where the [Demon King] was defeated by a [Hero] that came from another world. People carelessly forgot about their fear of the [Demon King] and of monsters, living in peace.

In a forgotten and run-down cave in the mountains, a new monster that should not have been born was given birth.

The monster’s name was the [Black Ooze]. It was nothing exceptional other than its black color, an ordinary slime.

However, this slime had the special characteristic of being able to take the abilities of the living things it swallowed. It preyed on an insect that had paralytic poison, as well as other animals. Following that, it attacked a human, obtaining his knowledge and [Desire].

Before long, the monster established its target as the female mage that came to explore the cave.

This world still wasn’t aware.

A mecha otaku is reincarnated into another world as Ernesti Echevalier (Eru). In this world there exist huge humanoid weapons known as Silhouette Knight. Dreaming of piloting those robots, Eru, with childhood friends, Archid Walter and Adeltrud Walter: together they will aim to become a Knight Runner, pilot of Silhoutte Knight.

In a world where everyone changes jobs, I actually awakened to a unique dual career.

And a life-defying career?

High-quality items to cherish? I synthesize directly.

Cherish high-quality skills? I synthesize directly.

Senior pet cherish? I continue to synthesize, wait, how did this beast girl become so big after synthesis?

Let’s start with the synthesis of three skeleton summoning books…

Synthesis – [Undead Army]

Three more dark staffs to synthesize…

Synthesis – [Death Scepter]

The game competition of billions of races in the universe, our solar system, can we earthlings stand on a broader stage!

…

- Description from novelbuddy