Mother Momoko has raised her only son, Kiyoshi, single-handedly, working hard to support his dream of attending university. She works all day at a lunchbox shop from early morning until evening, then spends her nights cleaning office buildings. During a parent-teacher conference, Momoko learns of her son's poor grades and realizes that recommendation-based admission is impossible. When she pleads with the homeroom teacher to revise her son's academic records, he, overwhelmed by her mature allure, assaults her right in the classroom. Kiyoshi happens to witness the scene and is shaken with shock and rage upon seeing his mother being violated by her teacher. That night, haunted by the lewd image of his mother, Kiyoshi reflects deeply on his own emotions. This incident ultimately strengthens the bond between mother and son in unexpected, intimate ways.