Counterattack System appeared when I'm already At The Mahayana Realm - Chapter 235 - 234 Cloudwater Secret Area

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

After opening the ancient well in his backyard, Li Yin’s life has changed since then!

Sixth Prince Li Yin? 21st century otaku Li Yin? He can travel freely between the two worlds, what kind of life should he choose?

Harem? Hegemony? trickery? Is that all?

No! With the advantages of modern technology, he wants to build his fiefdom into the economic center of the world, and the world map will be filled with his colonies…

PS: This is written about the Tang Dynasty, but it is a parallel time and space. There is no need for historical burdens, and it will be a little different from the real Tang Dynasty. Please don’t be serious about the textual research party, because some small details like titles are annoying. This is not what I wanted, thank you!

- Description from novelbuddy

A girl who calls herself a demon appeared before a timid student named Fumio Kijima. The girl claims to be a campaign girl from the demon world and she gives him the ability to “summon a room” from nothing but thin air.

At first he doesn’t abuse his power and uses it as a convenient ability in his every day life. But one day he is bullied by his classmates under a false pretext and is made to suffer. In the past he would have wallowed in misery and cried himself to sleep, but now he had a power to call upon.

“I will make them regret it!”

Using his powers to summon his “room”, he begins his era of confinement and brainwashing to achieve his goals.

The Devil’s Den was Cosette’s favorite webnovel that she had followed for three whole years. She waited for updates, wallow in those empty days during the author’s constant hiatuses, cry and laugh with the characters; it was already a part of her short life.

Cosette really wished that the novel would never end despite that she was terminally ill.

But after three years, The Devil’s Den finally came to an end. With a reader as invested as Cosette, she had mixed emotions about the ending. Not that the ending was disappointing, but what disheartened her was the ending of her favorite character; the villain Maxen Devilsin.

One year later, Cosette took her last breath only to wake up in the body of the stunning Cosette Blac; the villainess of the novel The Devil’s Den, her second favorite character after the villain.

Granted with the opportunity to live in the world of her favorite novel before the main story starts, Cosette had a plan.

That was to simp over the characters and save her favorite characters whilst hoping that the female and male lead still have their happy ending.

In a world that was already written and events that were expected to happen whether or not they wanted to, can Cosette change the course of their lives? Was overwriting the characters' fate could save them? Or would it just give them a much worse ending than what the author had given them?

Watch Cosette as she tried to become the superfan and give the dark-themed story some light.