Japanese history textbook controversies involve controversial content in government-approved history textbooks used in the secondary education (junior high schools and high schools) of Japan. The controversies primarily concern the nationalist right efforts to whitewash the actions of the Empire of Japan during World War II. Another serious issue is the constitutionality of the governmentally-approved textbook depictions of World War II, Japanese war crimes, and Japanese imperialism during the first half of the 20th century. The history textbook controversies have been an issue of deep concern both domestically and internationally, particularly in countries that were victims of Imperial Japan during the war. Despite the efforts of the nationalist textbook reformers, by the late 1990s the most common Japanese schoolbooks contained references to, for instance, the Nanjing Massacre, Unit 731, and the comfort women of World War II, all historical issues which have faced challenges from ultranationalists in the past. The most recent of the controversial textbooks, the New History Textbook, published in 2000, which significantly downplays Japanese aggression, was shunned by nearly all of Japan's school districts. Textbook authorization system School textbooks in Japan are not written by the Ministry of Education. Instead, the textbooks for all subjects in elementary, and both lower and upper secondary schools are written and published by several major private companies. This system was introduced to Japan after World War II to avoid the government having direct authority over the written contents. Japan's School Education Law () requires schools to use textbooks that are authorized by the Ministry of Education (MEXT). However, each local education board has the final authority to select which textbooks can be used in their jurisdiction from the approved list. In Japan, potential school textbooks must pass a sequence of evaluations before receiving approval to be used in Japanese schools. First, textbook companies submit a draft of their proposed textbooks to the Japanese Ministry of Education. The Textbook Authorization and Research Council (), an official council of the Ministry of Education, composed of university professors and junior high teachers, checks the draft in accordance with the Ministry's educational curriculum guidelines () to ensure that the contents of the proposed textbook are "objective, impartial, and free from errors." The Ministry of Education will give the company that authored the textbook the opportunity to revise the draft when it is found to contain information that is inconsistent with national guidelines. Once the textbook revisions