Working as a high school teacher while privately tutoring students at home, mother Sumire becomes involved in a forbidden relationship with one of her pupils. Her stepson, Kyohei, consumed by jealousy and rage, confronts and pressures her. Yet as Sumire tries to understand her son's feelings, she begins reflecting on her own emotions, facing new inner conflicts. Ultimately, a new relationship forms between mother and son, and hidden desires buried within their daily lives gradually intensify. An unnatural current of love flows endlessly, transforming their everyday existence into something entirely new.