L. Halliday Piel’s The Family State and Forced Youth Migrations in Wartime Japan (1937–1945):

Starting in December 1941, the National Diet began passing emergency mobilization laws that pulled male and female students out of middle school and high school to replace adult factory and farm workers who had been called to war. An estimated 3,100,000 students were called up to work in factories and farms. At first, it was limited to summer vacations or short-term shifts. By June 1943, the Tōjō Cabinet extended the shifts to boost aircraft production.

To that end, the 1943 Wartime Special Ordinance for the Factory Act was enacted to lower the minimum age of employment from sixteen to eleven. College deferments ceased; male university students had to enroll in the army. In October, the Koiso cabinet ordered schools to devote one-third of class time to labor service. The Emergency Student Labor Mobilization Strategy Outline of January 1944 (Kinkyū gakuto kinrō dōin hōsaku yōkō) paved the way for successive year-long shifts.

(Emphasis added.)

Imperial authorities forced dozens of thousands of Korean youths, in particular, to support the Axis war effort:

Yang had been a class leader at her school, excelling in athletics and academics. Her accomplishments did not go unnoticed by Japanese administrators, who offered her a chance for the future her humble family couldn’t afford.

“The Japanese principal said I could go to junior high school if I went to Japan. My father said he was lying and would not allow it, but I snuck away. Once in Japan, I never even saw the school door but was taken straight to Mitsubishi Industries, where I was worked nearly to death. I had wanted to be a teacher.”

Between 1937 and 1945, Japan employed millions of forced laborers throughout their occupied territories in Asia, and in mainland Japan as well. Yang worked at the Mitsubishi plant in Nagoya, from June 1944 to October 1945. Estimates suggest more than 500,000 South Koreans were forced laborers in Japan during the war.

Elderly Koreans have been struggling to obtain reparations, with little success. In 2023, surviving forced labor victims rejected S. Korea’s foundation-based ‘compensation’ plan.

(ETA: replaced the head URL with something more relevant.)