Tatsuo Igarashi, a college student living in Tokyo, stays at his aunt Shinobu Igarashi's hometown home along with his uncle Yasuhiro and his aunt Yuriko Shio, while his family's house undergoes renovation. Though living independently, Tatsuo enjoys the warmth of family life—until one day, when he returns home and becomes captivated by his beautiful, well-shaped mother, overwhelming him with intense sexual desire. Unable to suppress his urges, an illicit relationship begins to form between mother and son. Meanwhile, Yasuhiro shares an intimate bond with his widowed mother, and as their desires intertwine, both relationships grow increasingly twisted. Witnessing each other's mother-son affairs, their forbidden impulses deepen, driving them toward an unexpected and uncontrollable plan.