Sayuri Nishina, 43, a full-time housewife. My husband is in his prime and is often away from home, so our home is like a single-parent household. I spend lonely nights alone, and I find my fingertips on my crotch... But one day, my son sees me like that. Unable to suppress the heat in my crotch, I invite my son into my room... It's a secret between the two of us, and if my husband finds out, it's over.