A young boy’s idolization of a sailor leads to a violent confrontation between romanticized ideals and the harsh reality of domestic life. Noboru, a thirteen-year-old boy, observes the world through a peephole in his bedroom, viewing his widowed mother’s life with detached scrutiny. When his mother begins an affair with Ryuji, a sailor who represents the masculine ideal of freedom and the sea, Noboru initially welcomes the intrusion. However, as Ryuji prepares to abandon his maritime life for a conventional domestic existence, the boy and his peer group perceive this transition as a betrayal of the sailor’s noble nature. The narrative follows the boys as they formulate a cold, calculated plan to preserve the sailor’s integrity through extreme measures.

Readers frequently highlight the stark contrast between the lyrical descriptions of the sea and the clinical, often disturbing, psychological development of the adolescent characters. Discussion often centers on the philosophical implications of the boys' actions and whether they represent a genuine pursuit of purity or a manifestation of sociopathic detachment. Critics often point to the author's ability to maintain a sense of impending dread throughout the narrative, even during moments of apparent domestic tranquility. The work is widely regarded as a significant examination of the tension between the desire for heroic transcendence and the mundane reality of adult life. Readers often note that the prose remains disciplined and sharp, avoiding sentimentality while addressing complex themes of betrayal and identity.