I am that male friend in the harem story - Chapter 9: Is it a new beginning?

A man is reborn into the world of Avatar: The Last Air Bender as a waterbender from Katara's tribe. Best of all, he was the same age as her, and he had a system with him to help.He knows the future and a system that lets him continuously get stronger by completing quests or long-term missions, as well as giving him the ability to copy abilities from others for himself. He will become invincible in the world of Avatar, even more so than the Avatar himself.

When disaster struck, Ling Mo knew that the kinds of zombies depicted in doomsday movies would in fact, be totally different from reality…

She was stupidly in love with him. Because of him, she became rude and unreasonable, overbearing, jealous, insane. But he did not spare a glance to her. Married for two years, he didn’t favor her once, letting her become the laughing stock of the whole world. Eventually, she ended up in an affair, leading to her tragic death.

Shaymon, the man who has achieved the apex of dark magic, is framed as being a Demon King and is killed.