A group of five young men who have been gifted with mystical, superpowered samurai armor in order to fight against an otherworldly invasion from the "Phantom World," a dark dimension headed by the evil warlord Arago. Arago (who in his initial incarnation appears as a giant spectral, glowing helmet, and later grows to gigantic size) was originally vanquished centuries ago in his first invasion attempt by a holy man who later appears in the series to counsel the heroes. Arago's henchmen also wear mystical armor, each with different weapons and a different specialty. It is revealed later in the series that both the heroes' and the villains' mystical armor are parts of the same ultra-powerful suit of armor that was broken up when Arago was originally defeated, creating an interesting good vs. evil dichotomy in the warriors' own arms and armor.