Which of the following countries primarily practices civil law?

Japan primarily practices civil law as its legal system is largely influenced by the civil law tradition, especially stemming from the German civil code. The civil law system is characterized by comprehensive written codes and laws that serve as the primary source of law, rather than judicial decisions. Japan's legal framework includes detailed statutes covering various aspects of law, including contracts, torts, and family law, which is indicative of civil law systems.

In contrast, the other countries mentioned have different legal systems: the United States predominantly follows a common law system, which relies heavily on case law and judicial precedents. The United Kingdom also adheres to a common law system, with its law developed through statutes and case law. Canada operates under a mixed legal system, primarily based on English common law, while certain provinces incorporate elements of civil law, specifically in Quebec. This distinction reinforces Japan's classification as a country that primarily practices civil law.