A quiet couple, the Kurodas, live an ordinary life in a residential neighborhood. Their days pass without major incident, until one day, Mayo's phone rings. Though seemingly routine, her reaction feels off to her husband, who senses something unusual in her behavior. Mayo acts as if hiding something, leaving him no choice but to accept her explanation—for now. As time passes, her absence gives him opportunity. Driven by suspicion, he secretly checks her phone, slowly realizing that something is definitely going on.