Natsumi arrives at Noboru's house as his new stepmother. She is kind to him, beautiful, and boasts a stunning big-titted figure that makes her undeniably attractive. Noboru finds himself drawn to her, though he hides his feelings in front of his father. One day, his otaku pervert friend Kousaku comes over to hang out. Unexpectedly, Natsumi ends up joining them, revealing her hidden, lustful side. Yet what Natsumi truly feels runs deeper than mere desire. What lies beneath her true emotions…?