The Great Eye is an omnipotent being that had existed in the Gamma World before the Gamma itself would even exist. Long ago, the Great Eye chooses Adonis, the Gamma emperor who was depressed from the death of his wife, firstborn son and many of his comrades. Through the power bestowed by it, Adonis makes Edith's invention to transfer their peoples souls from mortal bodies to Eyecons a reality. But Edith's creation did not ensure immortality as intended and he could reach the Great Eye due to the Gammisers he built to guard the omnipotent being itself. If the Great Eye leaves the Earth, Edith's stasis capsule no longer active, thus returning the capsule's user to its human body.
In the present day, the Great Eye is first summoned when all 15 heroic Eyecons gathered at the Daitenkū-ji's monolith. Chikara Saionji planned to use it for his own agenda but was disintegrated and instead it picks Takeru, granting the boy's wish to resurrect Kanon instead of his own life. However, during the second time it is summoned, the Great Eye is protected by the Gammisers, preventing him from making a wish reviving himself. After combining with the Gammisers, Adel attempts to manifest the Great Eye's power but is incapable of doing so due to interference made by Edith, Adonis and Takeru Tenkūji being the main component required to do so. It is revealed that Great Eye is interest in Takeru Tenkūji on the entity's favor, due to his heroic deed as humanity's hope since their first met such as wishing Kanon return to normal, with Frey and Freya as his messengers to warn Takeru an upcoming dangers about to happen in the future. When the Demia is activated, Adel took control of the Great Eye and used its powers to turn everyone under the Demia Project within his control, which is actually part of Gammisers' plan on manipulating Adel for their true plan, until Takeru stopped him on time with the help of Alia and killed him under the former's own wish, when the Gammisers finally made their moves and possessing his body. But as it seemed that the Gammisers finally defeated, it was revealed that the Deep Specter Eyecon which belonged to Makoto's doppelgänger contained backup copies of them, and eventually possessed the Great Eye and use Freya's body to turn into Great Eyeser. After Ghost finishes Great Eyeser for good, the Great Eye and Freya are finally freed, thus granting Takeru more than one wishes as a debt before leaving Earth and entrust it to Takeru.
The Great Eye's true identity is the collective consciousness of intelligent extraterrestrial lifeforms, that evolved into beings without physical bodies.
The Great Eye and Great Eyezer are voiced by Yūi Fujimaki. As Great Eyezer is co-voiced by Sayaka Ohara.