Stranger's Handbook - Chapter 40: Zest, the Mentor

A man was transported to Ancient China and eventually became a servant of a declining household without a male heir. He utilized his wits and modern knowledge to help the household and eventually become trapped in the sea of political turmoils of the period.

- Description from Novelupdates

Zavier met Cosmic Consciousness after his death. He was satisfied with every system that Cosmic Consciousness exhibited, so he wanted all of them. Surprisingly, the Cosmic Consciousness obliged him.

Zavier was reborn in an isekai full of magic and alchemy. Now, he had many routes to upgrade. Interestingly, to coordinate these systems, Cosmic Consciousness gave him the gift of being able to duplicate himself. He could clone a finite number of himself to manipulate these systems.

Magus, Alchemist, Mesmer, Tamer, Hunter, Vampire, Werewolf, Dragonknight, Necromancer.....

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By the way, it wouldn't appear NTR or some bullshit harem of courtships. MC of course will have harem but not for cliches.

“Hunter Full Time”, who traveled to the top of the three high-risk worlds, obtained the trait-type telekinetic ability-the fruit of face, and began to live (zhuang) daily (bi) with a single sentence.

“Give me some face, let’s leave this matter alone!”

- Description from novelbuddy

A spin-off of the various works of Kamachi Kazuma. One day, Kamijou Touma (A Certain Magical Index) faced yet another misfortune. His toilet was broken and spraying water everywhere. As he was lamenting his misfortune, suddenly he appeared in a strange place along with Index and Misaka. Soon enough, more strange people begin appearing…

Includes:

A Certain Magical Index

Heavy Object

The Zashiki Warashi of Intellectual Village

The Circumstances Leading to Waltraute’s Marriage

A Simple Survey / A Simple Monitoring

Killer Princess and Deep End