Marie divorced her husband three years ago and lives alone with her son Satoshi. Recently, she's noticed a strange change in Satoshi's behavior. Unsure if it's just typical teenage development, she becomes increasingly uneasy when she catches him constantly staring at her buttocks, stirring deep maternal concern. Then one day, an incident occurs that will drastically shake their parent-child relationship. Marie's habit of wearing clothes that accentuate her backside inadvertently becomes the trigger for Satoshi's actions.