Seven brothers, Heeseung, a lawyer, Jake, a scientist, Jay, an engineer, Sunghoon, a wealthy CEO, Sunoo, a doctor, Jungwon, a teacher, and Niki, a substance user, fight their way to survival after each encounter an attack linked to the reading of their father's last will and testament.

What happens when two boys, Sunoo and Sunghoon, discover an unbreakable bond amid the challenges of their illnesses? Can this unbreakable bond defy the limits of their health struggles and create a story that resonates beyond the boundaries of a small world?