In a federal system, the central (or federal) government has much more authority than in a confederal system. The central government controls more trade policy, and makes decisions about policy areas that involve interactions between states (such as highway systems).
Nationality is a legal relationship between an individual person and a state. Nationality affords the state jurisdiction over the person and affords the person the protection of the state. What these rights and duties are vary from state to state.
Japanese nationality is a legal designation and set of rights granted to those people who have met the criteria for citizenship by parentage or by naturalization. Nationality is in the jurisdiction of the Minister of Justice and is generally governed by the Nationality Law of 1950.