When Jun gets home, his mother Yukari, who had just gotten out of the bath, greets him in just a bath towel. He thinks it's okay if she's his son... but Yukari's slight carelessness will greatly change the fate of the mother and son. When the bath towel is removed at an unexpected moment, she reveals a pure white buttocks that contrasts beautifully with her dark skin, so much so that it is almost mistaken for pure white panties. Jun, who had only ever seen his mother's tanned skin, is instantly captivated by the sight...