Saki Hanashiro's son has always been excited by his mother's big ass since childhood. Over time, his desire grew stronger, until one day he crept up on his sleeping mother, coated her back in oil, and started rubbing his dick against her to masturbate. Saki herself had a strong sex drive and regularly pleasured herself in the kitchen using vegetables, making it a daily habit. Her son had long noticed her actions. One day, news arrived that her husband, who had been living apart for work, would be returning home after a long absence. Overcome by the desperate fear of losing access to his mother's body, the son suddenly lunged at Saki from behind and shouted, "Mom's ass belongs to me! I won't let anyone else have it!"