The supporting character's harem is very normal - Chapter 156 New skill - Charring Field

In the tenth year after the new era, the world finally came to an end. Zhang Mu truefully waited for his death, but unexpectedly found that he had returned to ten years ago. With his memory about the future, he swore that he would change the calamitous history, saving the earth from being destroyed! Walking dead, zergs, evolvers, and various mutated animals… nothing can stop him! The first step is to retrieve his identity as an era merchant , then find all the treasures he can remember to enhance himself!

- Description from Novelupdates

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!

ln the Higher Realm.{Ehhh! It’s started?} an entity exclaimed.{Yeah, but like, what the hell—she gave the golden finger to him? Of all people, someone useless and a scheming bastard?} another shot back, clearly not having it.{Someone Immediately Stop him he's corrupting the system!} An entity roared before they could even get ready for see how had had been chosen!___On Earth.[System Integration... 1%A wicked grin spread across his face. This was his chance—a chance to do something no one in those web novels and mangas and animes had ever done. To corrupt the system!minute later....[System integration... 85%...][System integration... 99%...][Integration complete!] It ran one last time...“Did I succeed?”And so the journey started.

When he stayed at her home and one night, he took her body in a drunken stupor. From then on, he had been a constant fixture in her life. How adamant he was in forcing a marriage was how adamant she demanded for a divorce. “I’m not staying married to you! I’m not staying married to you! I’m not staying married to you!” After she repeated such an important proclamation three times, he finally tossed her the divorce paper. She thought she had finally escaped him alas… After the divorce, he still snuck into her room every night… Finally losing her patience, she yelled, “We are already divorced!” He glanced at her and set down the divorce paper before her. On it, it was written clearly: After the divorce, the car is hers, the house is hers, the company is hers, their child is hers, he… is also hers?