A miraculous technology called Advanced Regenerative Medicine can bring back what was lost. For her, it was a lifeline—a way to keep moving forward. For seven years, she has undergone the same procedure, year after year. But this year, something is different. She doesn't wake up in a hospital bed. Instead, she finds herself in a stone chamber, her body heavy, surrounded by silence—and by someone who looks exactly like her. Is this truly medicine? Or is it something else entirely? To protect those she loves, and to uncover the truth, she must face a choice that will change everything.

It’s summer, and Ca is living her typical life as a high school senior—commuting to school, sitting through the same classes, eating lunch with friends. But one day, a quiet question begins to stir in her mind: Is this world really what it seems? Through casual conversations and subtle signs of something being off, the question grows louder. Something isn’t right. She doesn’t know what it is yet—but she’s determined to find out. As she follows that thread of doubt, Ca uncovers a truth that will lead her to a final choice... one that could change everything.