Nippon is the ancestral homeland of the Iron Masters, located many thousands of miles to the west of North America. It was presumed destroyed in the War of a Thousand Suns.

According to the Amtrak Federation's records, Nippon was an island-nation known in Basic as 'Japan', located across the Pacific Ocean from North America. Japan's fate in the War of a Thousand Suns is unclear, but when combined with Iron Master traditions and histories, it appears that the nation suffered several direct hits from nuclear weapons and was mostly destroyed. However, enough refugees survived the conflagerations to reach the American continent, where they later founded Ne-Issan in rememberance of their lost homeland.

Iron Master myth records that their homeland was enslaved by the Dark Light (electricity) and became a place of decadence and corruption with people worshipping at the altars of consumerism and technology rather than holding to the honourable traditions of the code of bushido, as their ancestors had done. According to the Iron Masters, the sun god Amaterasu-Omikami destroyed the world in revenge for this hubris. As a result, Iron Master society outlaws all use of the Dark Light on pain of death, and promotes the values of honour and the warrior ethos over all else.

According to the same myths, the dominant geographic feature of ancient Nippon was Mount Fuji, a site of great spiritual importance. The hierarchy of Iron Master civilisation is based on the distance of the various ethnic groupings' homelands from Mount Fuji, with the Japanese making up the highest class of citizen and the Thais the lowest.

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