Sphere

The Spheres (Crystals in Japan) are four magical artifacts required to ascend the Tower and reach Paradise. The Spheres take on the color appearance of the Four Gods associated with them. Only when a hero acquires the sphere can they open the doors to the higher floors.

The Four Spheres

 * Black Sphere - Found in the First World, it is guarded by Gen-Bu and hidden within the Statue of the Hero. Only when the heroes obtain the King's Equipment and return it to the statue they belong on, will the Sphere present itself.
 * Blue Sphere - Protected by the Twin dragons of Sei-Ryu and Ryu-O, the two fought long ago and broke the Sphere into two pieces: The Red and Blue Orbs. Sei-Ryu protects his within his castle, hidden among several fakes. Ryu-O took the guise of a human and will only grant his piece once Sei-Ryu is slain and the player solves his riddles.
 * White Sphere - Once in possession of the Resistance Leader, he his the secret to it's location with his daughters Milielle and Jeanne. Bya-Ko seeks the White Sphere and has captured Milielle. His troops search for the secret location of her sister Jeanne. The White Sphere is somehow hidden within the sisters and will only appear when their tears meet.
 * Red Sphere - Is in possession of Sayaka, who grants it to the party once they rid her destroyed world of Su-Zaku.

Trivia

 * Unlike other Key Items within the game, the Spheres are placed in a special line beneath the Trash Icon, they cannot be removed, and and trying to use them opens a secondary menu where you can see the sphere and select them.
 * The colors of the Crystals are based on the colors associated with the Chinese Four Gods.
 * The four spheres are an obvious nod to Final Fantasy which often incorporates four crystals as a central point of their stories. This makes the fact that SaGa was released under the Final Fantasy Legend banner in the West more amusing.