Worlds Collide, Am I the Only One Who Can Save Them?

【Save the World】(Heart-Wrenching)(Happy Ending)(Transmigration) My older brother is dead, but a transmigrator came into his body and became part of my family. At first, I was deeply hostile toward him, but then everything changed. The world was overrun with zombies, yet even after Mom and Dad passed away, he never abandoned me... But my brother's friend tricked me into becoming a test subject, and my life was nearing its end. He blamed himself terribly, but at the most crucial moment, the world saved us. My brother sent me into space because he was afraid I might be in danger, but I was stolen away by the consciousness of another world's will. It forced me into a contract and made me save the world... I feel like I'm going insane. The world killed all my younger siblings, and even the little “me” starved to death right before my eyes. I know what utter despair feels like! “Go on, attack me! Why have you stopped trying to get in my way? Why?!” “Hahaha! Bai Zhu, I won...” “Bai Zhu, stop! You've already saved this world. You have no enemies left here!” “I want to go home. I just want to go home! Why?!”