Yuka has been single-handedly raising her son, Kosuke. While harboring evil feelings towards her son who is gradually becoming more and more like her late husband, she also releases her unfulfilled desires within herself. Meanwhile, Kosuke secretly harbors love for his mother that goes beyond that of a mother and son, but hides it and lives his daily life. However, on the night before his wedding, Yuka peeks at him masturbating and says, "This is the last night we'll spend together as mother and son..." as she gently strokes his stiff, erect cock. However, that alone is not enough for the two of them, and they can't contain themselves and are driven by forbidden lust...