Dai was the youngest of three brothers, and to his mother Maki, he had always been an easygoing child. But one spring, his older brothers left home for jobs in other cities, and his father was transferred for work, leaving the house suddenly quiet and empty. Now only Maki and Dai live together, and in the silence of their lonely household, Maki begins to feel a deep sense of loss. Watching her, Dai grows increasingly lonely and frustrated. Craving his mother's undivided affection, he decides to take action. The bond between mother and son begins to evolve into something deeper—and forbidden.