MTL - The Counterattack System is Only Available In the Mahayana Period - Chapter 36 give pointers

When Shen Xinghui, an ordinary young man, is suddenly transported to a fantastical world, he finds himself surrounded by incredible beings like Beast Man, Dragon Man, and even Demons.Struggling to adapt in a place where the rules of life, magic, and even biology are wildly different, Shen Xinghui must rely on the guidance of Ignatius, a noble Dragon Man.As Shen Xinghui learns about this world’s diverse cultures, powerful magic, and the ever-present mystery of how he arrived, he discovers that he’s not the first outsider to find himself here—and perhaps not the last.With no clear way back home, Shen Xinghui embarks on a journey to the capital of the Cindralith Kingdom, determined to carve out a place for himself in this strange yet wondrous land. Along the way, he uncovers secrets about the world—and himself—that will change his destiny forever.

After picking up a phone on the streets, Feng Yuchen was sent to the world of High School of the Dead. He, along with 100 people, have to travel through various worlds, fight and solve quests in order to survive.

Whoever dies in that world, would be teleported back to the real world without memories of what happened before and die in an accident one year later.

- Description from Novelupdates

Chen Rui, an otaku from earth, is reborn into a human body in another world, who falls into the legendary evil, brutal world of the devil called Mozu where humans are treated as food. He has to survive while facing horrors of the devil, violent dragons and a variety of powerful enemies by depending on a strange super system chip and his wits. Surrounded by Devil’s beauties such as black-bellied lolita princess, cold queens, violent dragons, charming poisonous devils …

Wanting to live in the Devil’s world is hard! Wanting to live in the Devil’s world as a human is harder! Wanting a human to be the devil’s son-in-law is hardest!

Let us see how a small otaku uses power and strategy step by step starting from an ordinary human to writing a legend as the devil’s greatest son-in-law.