Emerald Weapon (エメラルドウェポン, Emerarudo Wepon?) is a recurring enemy in the Final Fantasy series. Originally appearing as a superboss in Final Fantasy VII, it has since made cameos in other installments as well.
Emerald Weapon is one of two superbosses first introduced in the North American release, and later appearing in all succeeding versions of the game, alongside Ruby Weapon. Fought under the sea by ramming it with the submarine, it boasts the highest HP of any enemy in the game at a staggering 1,000,000, and is one of few fights in the game fought under a countdown, 20 minutes without the Underwater Materia. It attacks with powerful non-elemental attacks, the deadly Gravity-type Emerald Beam, and the powerful Aire Tam Storm. Defeating it yields the Guide Book item, which can be traded for a full set of Master Materia with the Kalm traveler.
The still-frozen Emerald Weapon appears as an Easter egg, buried in Banora Underground. In the northern sections of the first area, "Depths of Judgment", Emerald Weapon's shoulders emerge from a large formation of crystal. The ridges and slots on the shoulders for Emerald's four orbs identify it, but the player is unable to move Zack or the camera in such a way as to see past the crystal.
Emerald Weapon lies beyond the map borders, and the player cannot get any closer to it other than this distant view. The same Emerald Weapon sighting might be encountered on background in mission 9-6-6, during the battle with superboss Minerva.
According to the Crisis Core Complete Guide, the Banora mining site was closed when Shinra discovered Emerald Weapon in stasis underground, and the village was built to hide the discovery with Shinra staffing it with residents.