Help the Hero, Don't Fall for the Villainess

The last thing Kai had expected when he had died, was to wake up in the world inside of a story he had read as a background character. And it wasn't just any story, it was the story that his sister had written before she had died. Determined to live this new life to the fullest, Kai grew and went on to become an employee at the male lead's company. Additionally, he was able to become the male lead's and female lead's friend.

Caught up in the stableness and blissfulness of his life, Kai had forgotten that the plot of the story had yet to begin and was reminded when he stumbled upon a scene he shouldn't have seen involving the villainess. Deciding to make it easier for the story to finish completely and give his friends their happily ever after while at the same time wanting to get this problem off his shoulders, he teams up with the male lead to spy on the villainess, Valerie Ashton.

His goal was to help the leads get their happily ever after, so why... was he finding the villainess attractive? Why was he hesitating in his plans to bring her and the villain down? Why was he finding that his sister's story had hidden so many things and was going against it?

Could Kai change the story in order to give everyone a happy ending, including his with Valerie?