The Egg is the main villain from SaGa Frontier 2. It is a mysterious, sentient artifact that corrupts anyone who carries it; while granting them supernatural powers and consuming the Anima from anyone killed by its power. The Egg has a conscience of its own, being able to talk through the person in its possession, using it like a puppet. It shows a strong desire to kill Wil Knights (one of the two main characters) no matter what, due to him constantly thwarting its plans. Wil can sense the presence of the Egg, in the same way the Egg can sense his. Its true motivations are unknown.
Prior to the beginning of the game, The Egg was locked deep within the Desert Megalith, but was found by a group of adventurers composed of the father of Wil Knights and the Sergein Brothers. They all fought over possession of the Egg, but Alexei Sergein claimed it and killed everyone else. Wil Knights eventually becomes a treasure hunter in order to investigate the circumstances of his father's death.
Wil eventually gathers information about Alexei and pursues him, confronting him at the Quarrysite, where he makes him fall into a chasm. The Egg then goes missing, but later on Wil hears rumors about a group of pirates who are in possession of the artifact, so Wil pursues them and sink their ship along with the Egg.
After twenty years, Wil's son Rich, who also became a treasure hunter, eventually learns that the Egg is now in possession of a mysterious girl, so he decides to investigate her. Rich finds the girl, Misty, who is under the Egg's control, but she lures him into the Insect Megalith, where she simply hands over the egg to him while she kills her. Rich then realizes the Egg has already consumed his Anima, so he jumps to his death to not let himself be controlled by the Egg.
14 years after Rich's demise, his daughter and Wil's granddaughter Ginny also becomes a treasure hunter and learns about the circumstances of her father's death while exploring the Insect Megalith. As she tells Wil about it, he finally tells her about the Egg. The two learn that the Egg is now in possession of Fake Gustave, an impostor of Gustave XIII (the other main character of the game) who is trying to take over Gustave's kingdom. They watch as Fake Gustave's army is defeated by King David, but both Fake Gustave and the Egg are nowhere to be seen.
Ginny and Wil learn that Fake Gustave and his remaining henchmen have fled to the northern continent. They go to the continent as well, but Fake Gustave is missing. The group find the entrance to the Final Megalith, where they finally confront the Egg, which assumes a series of monstrous forms to fight them. They defeat the Egg once and for all, but as they flee the place they find the Egg resting on the outside. As both Ginny and Wil don't know what to do, Gustaf, Gustave's nephew, raises Gustave's Sword, a huge Greatsword made of pure metal which uses no Anima, and attacks the Egg. Though the sword breaks in two, the Egg cracks and explodes, releasing all Anima it had consumed for years.