Saki, a wife, lives happily with her husband Yoshiro and father-in-law Naeru. The perverted old man Naeru gazes at Saki's plump hips and indulges in naughty fantasies. One day, a sudden tragedy strikes Saki. While masturbating, a thorn gets stuck in her precious bottom! Even after looking in the mirror, she can't find the thorn, and unfortunately, her husband is on a business trip and won't be back for a while. Saki is at her wit's end, so she makes up her mind and asks Naeru to remove the thorn, but...