A core principle of Japanese culture is that healthy and virtuous living necessitates that one cultivate thoughtful moderation in the treatment of inanimate objects. The two most popular and influential religions in Japan, Shinto and Buddhism, both caution against the opposing vices of wastefulness and unhealthy attachment. Clinging attachment to objects is anathema to Shinto ideals of spiritual purity; they are also a major cause of dukkha, or suffering, which prevents enlightenment in Buddhist teachings. In turn, certain yokai, or spirits, in Japanese folklore punish wastefulness; traditional disposal ceremonies at Shinto and Buddhist shrines encourage respect and reverence for objects even once they’ve outlived their usefulness. The Japanese expression mottanai, which expresses regret over wastefulness, has become a recent slogan in environmental protection campaigns.

The postman begins the novel as a man unduly attached to his possessions, and unfairly dismissive of their importance of objects. He is aghast at the thought of surrendering prized collections of comics or action figures, but willing to sacrifice useful everyday items like phones. This reflects his attitude to interpersonal relationships; he holds on to strong emotions for his loved ones, but does not take time to maintain the relationships as he goes through his days.