A chance reunion with her childhood friend Kyō, whom Eriko had parted ways with 20 years earlier, becomes the turning point in her life. Back in school, Eriko was deeply in love with Kyō, but on the day of their first date, he suddenly vanished without a trace. The truth behind that incident remains shrouded in mystery, and eventually, Eriko married Jōshi, Kyō's best friend. The hidden love triangle between the three has left lasting scars, even after two decades. Now, faced with the reappearance of Kyō and her enduring love for her husband Jōshi, Eriko struggles to remain loyal. Torn between guilt and forbidden desire, a new and dangerous relationship begins to unfold.