Kayo Kishimoto (25 years old) works for a company that sells used office equipment.Despite having a boyfriend of her age, she secretly continues to think of her father-in-law, who is quiet and moderately muscular and lives with her.Although she doesn't want to destroy the family, she imagines her father-in-law's strong cock whenever she has free time and is absorbed in masturbation.The more she rubs her finger against her pussy, the more her desire for her stepfather grows.One day, she receives good news that her mother will be home three hours late...