When 10-year-old Yamato and his friend Miku stumble upon a wounded man in a secluded alley, their lives take a dark turn. With his dying breath, the man discloses a shocking revelation to Yamato - his father was the mastermind behind a notorious bank heist, shrouded in mystery for decades. As the man cautions them to be wary of everyone, Miku implores Yamato to guard this secret closely. Soon thereafter, Yamato's father meets a tragic end, leading to Yamato being embraced into Miku's family. Despite the official ruling of his father's demise as an accident, Yamato harbors suspicions. Fast forward six years, and the enigmatic past continues to haunt Yamato, compelling him to seek answers and seek justice.