Kondo Hideki is 42 years old. As the only son of a pharmaceutical company president, his future had seemed secure. However, after being placed on leave last year, he now lives with his parents. What troubles him most is Reika, his father's mistress. Much younger than Hideki, she clings to his father in order to secure her position. Hideki's suspicion toward Reika has been growing intensely, reaching a boiling point. Then, when his father announces a temporary business trip and leaves Reika behind at the house, Hideki sees his chance—and moves forward with the secret plan he's been harboring.