"In 1448, Joseon invented a top secret weapon, singijoen."

The Divine Weapon

During the reign of King Sejong in the 15th century, the Joseon Dynasty was the embodiment of the perfect state. To the Ming China, the aspiring imperial power, Joseon presented an obstacle to territorial expansion. To protect themselves from war, King Sejong develops a secret weapon to defend their territory and take back their land and supremacy.