My Childhood Friend Turned Yandere in the Apocalypse

Rin was only five years old when he realized the truthhe had been reborn inside an apocalypse novel.But he wasn't the protagonist.He wasn't even a side character.He was just an extra'a wealthy, resourceful childhood friend of the story's heroine a girl destined to be dragged into the main character's harem and used until the end.Rin refused to accept that fate.If the world was going to fall apart anyway, then he would change the story before it even began. He would make her stronger. Independent. Someone who could survive without relying on anyone.That was the plan.But somewhere along the way, things went very, very wrong.Because instead of becoming an "independent and lovely woman"She became the No.1 hunter of the apocalypse.And she's completely obsessed with him.With a soft smile, she gently asks,"Rin, where are you going? I'll come with you."When someone gets too close, her smile doesn't fade as she says,"Who is this? Should I remove these annoyances for you?"She's strong. Beautiful. Unreachable.And utterly terrifying.Did I do this? Did I create the very monster I'm now trapped with?