Japan's government is a constitutional Monarchy, its very similar to Europe's Constitutional where Japan's Parliament is known as the "Diet". The government consists of The House of Councilors & The house of Representatives. Members of the Upper House are elected from national and local voters. Members of the Lower House are elected by just the local voters. When it comes to cities, villages, and towns have Governors and a elected "assembly".
The biggest issue that Japan's government is facing right now has to deal with the economy and how they are having a useless supply of unnecessary goods.
Major laws in Japan include no one over the age of 20 buy cigarettes or alcohol. Also those who are caught smoking out in public or drinking are heavily fined. For tourists they have a specific rule about not taking bikes that look they are put in the trash because, if you are found with it and it belongs to someone else the police will hassle you about it.