I Refuse to Become Scumbag in Tokyo - Chapter 20: Writer and Publishing House

A 30-year-old NEET is reincarnated into the body of an otaku that choked to death on instant noodles. As he comes to grips with his new life, he realizes that this world is subtly different from Earth. The denizens of this world are far better looking, and this new world also possesses futuristic technology as well as mysterious Yin Yang masters!

In her previous lifetime, they had married for five years. He meant everything to her, but she was thrown away like an old shoe.

After her rebirth, she gave him a divorce contract preemptively—

“Divorce after one year, the terms of the contract are as follows: husband and wife shall not share a room or bed. Intimacy forbidden?”

He raised his eyebrow.

Who knew that after she got drunk one day, leaning on the headboard, he rested his deep-set eyes on her. “You broke the contract, Mrs, Li.”

- Description from Novelupdates

Time travelling from the majestic era after the Recuperation of Reiki, he became Kimura Kazuki, a 16-year-old high school student in Japan, one year before the Reiki Recuperation.

Tentatively, he set out to hone himself to the bone, burning candles at both ends to stockpile resources in preparation for the imminent Recuperation of Reiki. His goal was to be many steps ahead of all humanity when the time comes.

However, it seemed like fate had decided to play a cruel trick on him.

One year later, the Recuperation of Reiki… did not happen as expected.

- Description from Novelupdates