I've Activated The Hidden Path of Beast Evolution - Chapter 13

The protagonist, Winnie (文尼), confesses his love to his childhood friend—the princess he’s been secretly in love with for years—but is brutally rejected in public. His heart shatters, he’s humiliated and ridiculed, and he collapses unconscious. When he wakes up, he vaguely remembers his past life’s memories and realizes he has transmigrated into the world of an otome game he played before. At first, he’s thrilled, thinking, “Nice! I must have been reincarnated as a villainous side character who disrupts the protagonist’s romance, right?” But then… surprise! He’s not just the villain—he’s the “Saintess”!

In this period where countless supporting lead actors always attempt to counterattack, turn over a new leaf or simply refuse to take up the role, his purpose of existing is to fill the role of a good supporting male lead and uphold his duty to the best of his ability. To add the needed lustre to storylines and this world. Only, it’s a pity that someone who is not afraid of god-like enemies will be afraid of pig-like teammates.

Bitterly, he realises that for some unfathomable reason, he is being bothered time and again by a bastard who refuses to follow the script… In order to walk the path of a good supporting male lead, he engages in a battle of wits and courage with that person. Loving each other and killing each other, one ultimately cannot escape fate’s teasing– why is it so difficult wanting to be a responsible and diligent supporting male lead?! QAQ

- Description from novelupdates

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.