Daiki never imagined waking up as Busujima Saeko's stepbrother in a brutal world overrun by zombies, where violence and chaos dominate every waking moment. Yet here he stands, thrust into this nightmarish reality teeming with gore and danger at every turn. His salvation arrives in an unexpected form: the Unreliable Choice System. This mysterious power grants him the ability to grow stronger by making critical decisions, earning rewards with each choice he navigates. Every decision shapes his path forward. But how will this dark, unforgiving world transform Daiki's fate? The true answer may already be within arm's reach, waiting in the shadows of his new life. As he learns to survive in a zombie-infested landscape alongside Saeko, the cost of his choices becomes increasingly clear.