The Heroine is My Stepsister, and I'm her Final Boss - Chapter 153 - 154: Fairy Core

This is the story of a young slave gladiator in an underground arena. He doesn’t know about his past or how he got to where he is, only that his name is Aegir, and that he is strong.

Entering Tokyo in the bubble era, in this strange era, the only familiar ones are Matsuda Seiko, Nakamori Akina, Kudo Shizuka…

- Description from novelbuddy

The King Of Assassins was a monster that reigned over the world of hitmen for long years. He was the absolute peak that no other being could reach. His name reached the ears of every powerhouse in the world and sent shivers through every human.

Yet, his legend came to an end suddenly when he died in unknown circumstances.

However, instead of disappearing forever, he was given another chance in another world by the goddess of reincarnation. It was the world of an old book that he read back in the time. A world where everything was possible, where humans could reach new heights that were impossible in his old life.

But, this place didn't seem to be normal as it carried a huge surprise that will make his journey seem all the more interesting.

The Goddess of reincarnation wasn't as holy as anyone would think. She was nothing but a twisted being who found a toy to play with. The goddess manipulated the world that he was going to and changed all the heroines into these twisted beings that fit her character. They were all now harboring this unhealthy obsession toward him and trying with all their powers to take him away for themselves.

When a young woman is killed in a traffic accident on her way home from work at a tax bureau, she suddenly finds herself transported to the world of the otome game she was playing the night before – but instead of the heroine, she’s been reincarnated as the bad guy! Using her knowledge of the game, “Iris” manages to avert personal disaster and decides to rebuild her life with her modern-day economic know-how. This is one mean girl who isn’t going to let her perceived reputation stop her from being a heroine!