The problems associated with the current Japanese bicameral system can be roughly grouped into: 1) the risk of a divided parliament, 2) the electoral system, and 3) the homogeneity of arguments between the two Houses of the Diet. The optimal solutions identified based on precedents in other countries are: 1) differentiation of the authorities of the two Houses (elevate the authority of the House of Representatives to a superior level), 2) differentiation of the methods of electing members of the two Houses, and 3) differentiation of the roles of the two Houses. These measures will reshape the Diet in a positive direction. The revision of the Constitution can be considered the best opportunity for fundamental reform of the Diet and the political system.