Rise of the Harem King - Chapter 39: Rivalry

Kusumi Chiharu gets a message one day that he has been selected as a Monster Tamer, and he is prompted to select his first partner. He thinks little of the message until he receives a giant package the following day. He assumes it’s the porn books he ordered, but the huge box ends up containing the unconscious body of a near-naked girl! She’s a ghoul named Zonmi, who intends to fight beside him as his partner.

However, it turns out that other hot girls at his mostly-male high school are also magical entities, and Zonmi may not be the only one who wants to fight by his side!

An ordinary student, a wretched peeper, a cowardly teenager with a kind heart. In a terrorist attack, he inherited the knowledge of countless elites, embarked on a path of God Jagged Tu…

He is an artist!

He is a mathematician!

He is a psychology Doctor!

He is a master of fighting!

In fact, he is a man

Taken off raw site:

A wretched, dirty young man is working during the summer when he was caught up in a mysterious explosion. After that explosion, the young man is then left with the memories and knowledge of dozens of the world’s experts.

He has changed, his heart has become cold, iron-blooded. He became a killing machine, his mind turned mechanical, calculative. Everything goes according to his plans and calculations!

In this magical, slaughterous world, a door is opened for him…

- Description from Novelupdates

[Warning: This story contains extreme violence, philosophical depth, psychological breakdowns, self-improvement, self-realization, and themes of maturity.]“Even Gods need character development.”That was the belief Pratham lived by—struggling, always pushing forward. Until the day he died, starving in a world too cruel to care.But death was only the beginning.He transmigrates and awakens in a multiverse as Leon. In this multiverse, the greatest threat to humanity isn’t demons or beasts, but Entities. In response, civilizations across each universe forged a single hope: the Entity Hunters Organization, training warriors to stand against the impossible.He had no magic. Just his will, his fists—and a little sister he swore to protect at all costs.Enrolling in the Entity Hunters High School, Leon finds comrades, purpose, and war. He fights beside them across different planets and universes, grows with them, laughs with them—then loses them all.Leon rises not as a hero, but something else.

In the age of Mecha for everyone, people could travel to the Endless Abyss to gather materials, enhance and forge their own Mechas, and thus wield the power to destroy heavens and earth.Jiang Chen had transmigrated and awakened the talent [Undying Barehand]. Once his Mecha shattered, he could permanently absorb its power and attain a multiple enhancement.…At the bottom of the abyss, the ancient demon god exerted great effort and finally broke the titan Mecha, but from the shards extended a hand that held down its head.“Congratulations, you’ve unlocked my restraints.”