After marrying Haruhiko and becoming stepmother to Aika, she becomes the guardian of his teenage son, Naoya. However, shy and reserved, Naoya refuses to respond to Aika's attempts to connect, keeping his heart closed off. One day, Aika witnesses Naoya being bullied by his classmates and goes to his room to comfort him. When she starts criticizing the classmates, Naoya suddenly erupts in anger—and forcefully takes her. An unthinkable secret unfolds between them. But Naoya confides in his close friend about the affair with his stepmother, shattering Aika's hopes for happiness. Soon, the secret spreads to Naoya's friends, dragging her into an uncontrollable spiral of desire and betrayal.