MTL - My Animation Era - Chapter 579 Original series (subscription required)

To correct the mistakes of his past, a young man is forced to narrow the space between science and witchcraft, as he ventures on a quest to save his world from complete destruction.

The Mirror World copies worlds close to collapse, forcibly taking its residents and giving them the goal of obtaining the ultimate stone, the Master Stone.Each race possesses a Race Stone, and Seong-Hwi meets his demise as he protects the humans’ Race Stone. However, he opens his eyes and realizes he has returned to the past.“It’s not unreachable. I just have to take the right path!”Seong-Hwi resolves to obtain the Master Stone and face his destiny head-on.Destiny is weak to the brave and strong to the cowardly. Become someone who grabs hold of his destiny.

agreed. He thought they might just talk, have a few drinks, and that nothing significant would happen. However, she invited him to a hotel, and they spent the night together.The next morning, she told him it was just a one-night stand and that they would probably never meet again. She said goodbye and left. Ronan also decided to treat it like that.The next day, at his college's hosting club, Ronan was given the responsibility of hosting that year's annual function, where they had invited a singer.When Ronan looked up at the singer, he was shocked—it was the same woman he had spent the night with. After checking her history and social media, he formed an impression of her. Every picture she posted was in revealing clothes, bikinis, or almost nude outfits.He concluded that she was just a promiscuous woman, likely driven by lust, and that she had probably chosen to spend the night with him simply because she found him handsome.Understanding this, Ronan decided to focus on his work. That morning, she had made it clear that it was just a one-night stand and nothing more. He would treat it exactly that way and carry out his responsibilities.Protagonist has System---No NTRIt's Harem, with many girls but The Singer is Main Heroine.

There is no master god, no system, no exchange, and some are just source codes that are fused in the mind to open up the world, not to be forced or suppressed, but to constantly go through in order to become powerful Look at my infinitely powerful source code …

- Description from uukanshu