Japan was one of the nations involved in World War II and was an Axis power fighting against the rivaling Allied powers. In 1944, a Japanese polit named Ikari Gunpei battled against American pilot Hank Marlow after they crash landed on Skull Island after a dogfight. They sparred until Gunpei got the upper hand and nearly killed Marlow until they were interrupted by Kong's arrival. Sometime later, Gunpei and Marlow put their country's differences aside and became friends, though Gunpei was later killed by a Skull Crawler, much to Marlow's dismay.
In 1999, at a nuclear plant in Janjira, MUTO 1/Hokmuto inadvartenly caused the power plant to collapse which killed Sandra Brody and several others. Ford Brody was present at school near the plant and was evacuated along with the other students and staff. The incident was covered up as an earthquake and the Janjira area was quarantined and Monarch had established a research site at the plant's location to study Hokmuto.
In 2014, Ford traveled to Tokyo to visit his father, who became obsessed with the incident and wanted to unveil the truth behind it all. The two of them traveled to Janjira, which is now abandoned and covered in vegetation.