Apocalypse Trade Monopoly - Chapter 3: System Reboot

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

- Description from Novelupdates

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.

I want an S-Rank skill too! I want it so badly, I could die for it!

Eh !? WHAT IS THE POINT OF GETTING ONE IF I DIE !?

Zhou Heng drank too much wine, and woke up to find that he had time-traveled, and there was a beautiful woman lying beside him. Just when Zhou Heng, a bachelor of ten thousand years, wanted to take charge, he suddenly discovered that this woman who had a relationship with him was called Sadako, and she was the Sadako in Midnight Ring.

Sadako is just Sadako, pretty and human, but the memories that come out one after another make Zhou Heng discover that his name is Takeo Saeki, and he is the husband of Kayako in the Grudge of the Great Evil Spirit.

Later, at work, Zhou Heng discovered that his female colleague had a strange identity. The daughter of his client, Mimiko Mizunuma, had always been very interested in him when she came into contact with him.

- Description from novelbuddy