The construction of the temple was in the autumn of the second year of Shokei (1290) at Oishi-gahara (a field with big stones) provided by Tokimitsu Nanjyo. Looking at clearing-up beautiful Mount Fuji, Nikko Shonin was remembering the will of Nichiren Daishoin; "The Kaidan of Honmon-ji Temple will have to be built at Mount Fuji." (The Lifetime Work Inheritance).
Nikko Shonin decided that this temple should be the sanctuary of Nichiren Shoshu to save the world of Mappo Ages and named it Dai-nichirenge-san Taiseki-ji Temple (The Big Stone Temple at Mount Fuji); Dai-nichirenge-san is another old-name of Mount Fuji because the crater of the volcano looks like a lotus flower with eight leaves. Additionally, Nippon (Japan) means the country of the Sun, however, it also can be read the main country of Nichiren (Daishonin).
Taiseki-ji will be renamed to be Honmon-ji on the day of Kosen-rufu when the whole earth will become the sanctuary with Nichiren Daishonin: the mystic law of Nam-myoho-renge-kyo can be applied not only human beings but also materials (including dead), other livings, societies, countries and the whole universe.