Short answers, pulled from the story.
The earliest recorded export of an enslaved person from Japan appears in the 3rd-century Chinese text Wajinden, which refers to slaves as seikō, meaning "living mouth." By the 8th century, formal laws under the Ritsuryōsei legal codes governed a class of enslaved people called nuhi, estimated to have made up around 5% of the population.
The Portuguese slave trade in Japan began after Portuguese traders first made contact with Japan in 1543 and was formally banned in 1595. King Sebastian I ordered a ban in 1571, but merchants largely ignored it and the trade continued into the late 16th century despite repeated prohibitions.
Toyotomi Hideyoshi issued the Bateren Edict on the 19th of June 1587, ordering the expulsion of Christian missionaries from Japan. Historian Rômulo da Silva Ehalt argues that Hideyoshi's primary concerns were economic, including fears of labor depletion in Kyushu, rather than moral opposition to slavery. Notably, Portuguese merchants who actually conducted the slave trade were explicitly exempted from the edict's sanctions.
Approximately 670,000 Koreans were conscripted under Japan's National Mobilization Law between 1944 and 1945. About 60,000 of those taken to Japan died between 1939 and 1945, mostly from exhaustion or poor working conditions. Total deaths among Korean forced laborers across Korea and Manchuria are estimated at between 270,000 and 810,000.
The comfort women system was a network of military brothels operated by the Imperial Japanese military during World War II, widely described as involving sexual slavery. United States House Resolution 121 estimates that as many as 200,000 women, mostly from Korea and China but also from the Philippines, Taiwan, Burma, the Dutch East Indies, the Netherlands, and Australia, were forced into the system.
In 2018, South Korea's Supreme Court ruled that Japanese companies including Mitsubishi Heavy Industries owed compensation to Korean workers for forced labor during the colonial period. In 2021, UNESCO reprimanded Japan for failing to adequately acknowledge the use of Korean forced labor at heritage sites including Hashima Island, part of the Sites of Japan's Meiji Industrial Revolution.