The Reincarnated Assassin is a Genius Swordsman - Chapter 529

Once an imperial princess, now reborn among the lowest of s*aves of the nobility.

This is a story about the protagonist getting the system, going crazy in the biochemical apocalypse, producing aircraft and tanks, destroying zombies, saving good people and killing bad people.

- Description from novelbuddy

It was an enormous tsunami that completely covered the sky, and due to its dark water, the sun had been blocked out. A sense of despair ran through everybody as they looked towards the peaked wave quickly crashing down. But was I the only one who noticed the massive sea monster lurking towards the front of the wave? CRASH [Requirments Met] [System has been chosen] [Your god has been selected] [System Granted] [Poseidon System is being installed]

Arnold never thought his gaming skills would land him in a romance novel—as a doomed side character, no less. To survive, he hijacks the heroine's “system,” bending the story to his will. But when he dodges a deadly duel, he catches the eye of the heroine, Lara, his own step sister—and her love is a dangerous game. Arnold must outwit the plot and his step sister who's not afraid to kill for love. In this LitRPG romance gone wrong, survival isn't just about beating the system—it's about escaping the heart of a yandere.