The episode details the history of the Honjo Masamune, a legendary Japanese sword forged around 1300 by Gorō Nyūdō Masamune.

Its unique construction, involving extensive steel folding, made it exceptionally effective against Mongol armor. The sword's significance extended beyond its military use, representing both artistic mastery and the samurai's spirit.

Passed down through generations of Shoguns, it mysteriously vanished after World War II, leading to speculation about its current location and value.

The episode explores the sword's creation, historical importance, and eventual disappearance, leaving its fate uncertain.