Age rule under Japan’s Juvenile Act

Japan’s Juvenile Act age rule establishes an age-based boundary for criminal culpability, but the novel presents that boundary alongside a more difficult question: how responsibility can be assigned when a person’s formation is shaped by trauma and circumstance. Kido accepts the rule’s distinction while rejecting the idea that turning nineteen erases the influences accumulated during childhood.

The Rule and Its Boundary

As Kido considers the possibility that children might one day commit serious crimes, he recalls that Japanese criminal law places anyone under nineteen under the Juvenile Act and regards only perpetrators older than nineteen as culpable. The rule provides a clear legal threshold, separating childhood from adult criminal responsibility by age.

The narrative does not treat that threshold as an answer to the wider question of how culpability develops. Kido reflects that negative influences do not vanish at adulthood as if a debt had been reset to zero. The legal boundary is definite; the consequences of a person’s earlier experiences are not.

Kido’s Reflection on Responsibility

Kido’s thoughts arise while he watches children playing. He imagines that one of them might someday kill someone, whether driven into a corner or acting through ignorance of what is right, and wonders who would bear responsibility. The possibility unsettles the confidence of any simple division between innocent childhood and culpable adulthood.

He compares the question with the case of Kenkichi Kobayashi, wondering whether Kobayashi at five might have seemed like an ordinary innocent child, while also considering that his pain and trauma may already have been visible. Kido thinks, too, of the ten-year-old perpetrators in the James Bulger case and the appalling conditions in which they grew up. Public pressure to punish them does not, in his view, settle the question of how their lives shaped their actions.

Nature, Environment, and the Limits of the Threshold

Kido considers whether individual effort alone explains a person’s direction in life, or whether that direction also depends on encountering the right people and events. Nakakita’s view—that character emerges through the interaction of genetic and environmental factors—accords with Kido’s own, as does his rejection of the claim that everything is solely the individual’s responsibility.

In this context, the age rule marks a legal limit without resolving the moral and social questions around responsibility. The novel places a formal classification beside the persistence of childhood experience: reaching adulthood changes the law’s treatment of a person, but does not reset the history that helped shape that person. The rule therefore serves as a point of departure for Kido’s broader inquiry into how responsibility should be understood across a life.