My Stepmom's Daughter is My Ex

High school was supposed to be a fresh start, a chance to leave the painful memories of a disastrous middle school romance behind. However, that hope is shattered when the protagonist discovers his ex-girlfriend not only attends his new school but has also become his stepsibling after their parents married. What he envisioned as a peaceful sanctuary quickly turns into an inescapable reality, as she is now everywhere—in his home, his classrooms, and his daily life. To make matters worse, she audaciously claims to be the older sibling, a challenge he firmly refuses to accept given his position in their newly blended family. Despite their shared history and the feelings they once believed were love, both teenagers have seen each other's true colors and recognize they are fundamentally incompatible. They understand that their past relationship cannot and will not be rekindled. Yet, for the sake of their unsuspecting parents, they must maintain the facade of friendly, cooperative siblings. Beneath this carefully constructed act, however, lies a quiet determination never to return to the way things used to be, turning their everyday lives into a constant test of boundaries and restraint.