After her husband's death, Tomosaki has been raising her family alone. To Hiro, she is an irreplaceable figure, yet her growing relationship with dance instructor Tsukakoshi deeply unsettles him. Though Hiro treats his mother with kindness, behind her back he mocks Tsukakoshi with vulgar words, harboring intense resentment toward him. When Tomosaki finally rejects Tsukakoshi's marriage proposal—partly influenced by Hiro's feelings—Tsukakoshi retaliates with a cruel and reckless act. Hiro stands up to protect his mother, but the confrontation only deepens the darkness within him. This story explores complex emotions, delving into the blurred lines between love and hatred, and the forbidden bond between mother and son.