Seo Jun-Hyuk, a young man tormented by relentless bullying, finds his life turned upside down when he unexpectedly awakens in a post-apocalyptic China. There, he discovers he is an expert martial artist with unparalleled strength. What starts as a fight for survival soon becomes an extraordinary double life as Jun-Hyuk gains the ability to travel between the decimated world of China and modern-day Korea, every time he falls asleep or wakes up. His journey of becoming the strongest in both worlds begins now.