Keiko Hirai was surprised to see a letter addressed to her and her husband from the Self-Defense Forces, urging their 15-year-old son to enroll in a special high school run by the Ground Self-Defense Force after graduating from junior high.

Wondering how the SDF obtained the address when Japan has a strict data privacy law, the letter revealed the information came courtesy of the SDF law and the Resident Registration Law, which allow municipalities to give the SDF access to the resident registry without a citizen's consent. Such recruiting letters are legal as long as they do not directly address minors.

At the high school referred to in the letter, students are not SDF personnel and do not engage in any SDF operation, but they take combat and arms-related classes on top of regular classes and are paid a monthly salary of ¥94,900 as public servants.