This Text Adventure Game is definitely poisonous - Chapter 1571 - 675: The Mechanic’s Ending_2

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.

She transmigrated into an orphan, thinking that she still had her boyfriend with her, yet in an instant, her world crashed. For the position of heir, he said, “Yao’er, why don’t you become my second wife?” A sentence destroyed her wishful thinking, causing her to end their relationship of two lives cruelly. Leaving the hustle bustle, she then lived in a forest, wanting to find an honest man to spend the rest of her life with. But not long after getting married, she realized that the honest man she married was a bit dishonest.

“Are you not an ordinary hunter?” she stared at the man pretending to be innocent in a furious manner. Is the ending going to be this way? Of course not, the story had just begun from the moment she changed her future.

- Description from Novelupdates

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.