The Great Will (宇宙の大いなる意志 and 大いなる意志) is an entity in the franchise.
- Megami Tensei II
- Shin Megami Tensei II: as 宇宙の大いなる意志
- Shin Megami Tensei III: Nocturne: as 大いなる意思
- Shin Megami Tensei IV: as 理
- Shin Megami Tensei IV Apocalypse: as The Axiom in the English version (大いなる理)
- Shin Megami Tensei: Strange Journey / Redux: as 大いなる意思
- Last Bible (Game Gear): Final Boss (true ending) as the Universal Will
Their Avatars' personalities are often very similar to YHVH; They appear as godly beings that stand on a high moral ground and present themselves as the road to salvation, but are ultimately ruthless, arrogant and cruel, only caring for their power and long standing regardless of any cost. Most of them are extensions of YHVH's will rather than separate from him, and as such often act on YHVHs behalf. Those that are not tend to take YHVH's place as the God of Law and are similar in personality. The sole exception is during Shin Megami Tensei IV Apocalypse where they are known as the "Axiom" and are depicted as largely benevolent neutral forces. During that time, they kick YHVH out of the group, and assigned Flynn and Nanashi to kill him.
Usually, avatars of the Great Will appear as the Final Boss of the games they are in, as well as their main antagonist. However, a few appear as recurring endgame bosses.
It is implied that, blinded by presumptuousness, YHVH and his avatars/extensions do not fully grasp the Great Will as they claim. They acknowledge that the Great Will produced them to rule the universes on its behalf, but fail to understand that their eventual demises at the hands of the protagonists is also the will of the multiverse, as explained by Stephen in Shin Megami Tensei IV Apocalypse.
Megami Tensei II
First mentioned in Megami Tensei II, upon defeat YHVH states that He is only a small part of the entity which rules over infinite universes, and that its vast consciousness will simply recreate His body, promising the hero that he has ensured the harshest path for humanity's future.
Shin Megami Tensei II
YHVH again references the Great Will after being slain by Aleph, promising that as long as humanity believes in His salvation the will of the universe will revive Him over and over.
Shin Megami Tensei III: Nocturne
Kagutsuchi, acting on behalf of the Great Will, causes the Conception and creates a Vortex World from Tokyo. The purpose of the Vortex World is to facilitate the death and rebirth of universes, as determined necessary by the Great Will.
During the Labyrinth of Amala sidequest, Metatron appears on the Great Will's behalf and tries to deter the Demi-fiend's progress, and is described by the demons of the Labyrinth as having the voice of the universe.
During the sidequest, Lucifer explains the Great Will's actions and the nature of the Conception. Since the Demi-fiend is neither human nor angel, he will be less likely to be blessed by the Great Will.
By venturing to the Fourth Kalpa of the Labyrinth of Amala, the Demi-fiend will be informed that Jyoji Hijiri, a reporter who has assisted him throughout the story, actually died when the Conception occurred, having failed to reach the hospital in time. However, he continues to exist in the Vortex World in the body of a Manikin as his punishment for committing the "ultimate sin." Hijiri is trapped by the Great Will in an endless cycle of suffering, death and rebirth, forced to witness the creation and destruction of each world without having any chance to affect the outcome.
Should the Demi-fiend choose to reject all the reasons, complete the Labyrinth of Amala and meet Lucifer, he will unlock the sixth ending - the 'True Demon Ending'. After defeating Kagutsuchi, Lucifer remarks that by defying the Great Will and choosing to side with him, the Great Will shall curse the Demi-Fiend for eternity, implying that he will suffer the same fate, or worse, as Hijiri. However, Lucifer will also comfort the Demi-fiend, stating that even if the Great Will cursed him, he'd have the blessing of the fallen angel. The Demi-fiend then leads the legions of Chaos in the final battle against the Great Will.
Shin Megami Tensei IV
While not directly mentioned, Lucifer states that people's thoughts are responsible for creating the Expanse, and that similarly humans are the reason that entities like YHVH will never disappear, suggesting that the Great Will is connected to reality.
Shin Megami Tensei IV Apocalypse
The Great Will is referred as the Axiom in the English version of the game. Unlike in previous incarnations of the entity, the Great Will is benevolent in Apocalypse and YHVH is no longer a part of it.
It is the cosmic force that is reality itself, upon which all universes and lifeforms exist within it. It observes reality through the eyes of messiahs. Although typically making only one at a time, this time the Axiom created two messiahs: one was Flynn from the Eastern Kingdom of Mikado and his previous incarnations, and the other Nanashi from Tokyo, who was the reincarnation of Akira and later became known as King Aquila of Mikado. In response to the cries of humanity who suffer in the Universes bound to YHVH's Covenant, the Axiom aided the messiahs who can be Godslayers to lead to YHVH's defeat.
The Axiom bestowed upon humanity the power of Observation when they were created, allowing them to give form to their beliefs and thoughts. This ability allows them to influence the world and is why gods and demons seek to use them. Despite all this, the Axiom is not sentient in a way humans would understand, which is why each side has interpreted it differently. Only Transcendent beings like Stephen understand the Axiom.
"I am the will of the universe. I am the whole of it, and at the same time, I am but a single part of it."
In Last Bible the final boss of the true ending is named the Universal Will. Before the final battle, the Universal Will states that he created El to be His adversary, that they exist to destroy each other, and challenges El to fulfil his destiny.
Upon His defeat, the Universal Will pontificates on the nature of the universe, how countless worlds are destroyed and countless more reborn. He tells El that the humans have earned a new world for themselves, and promises that they will meet again untold thousands of years in the future.
- Ancient of Days
- Metatron (Strange Journey only)
- Shekinah (and by extension The Wise Men)
- It is mentioned that Catholic Churches are specific places where people worship the Great Will in Devil Summoner 2: Raidou Kuzunoha vs. King Abaddon. This, however, appears only in the English localization and is absent from the original Japanese script. 
- Canopus acts as an alternate equivalent to the Great Will in Devil Survivor 2.
- The Persona 3 Club Book also makes a quick mention of the Great Will, stating that gods and demons emerge from humans as another means to defend their psyche from Nyx.
|Playable Characters||Aleph/Hawk - Hiroko - Beth - Cerberus - Lucifer - Satan|
|Non-Playable Characters||Okamoto - Gimmel - Zayin - Stephen - Haneda - Daleth - Red Bear - Madam - Hanada - The Center's Bishop - The Four Elders - Mekata - Puck - Hanoun - Mutant Elder - Hiruko - Taira no Masakado - Siren - Petersen - Michael - Raphael - Uriel - Gabriel - Fake YHVH - Seth - Virocana - Ozawa - Gotou - Gemori - Astaroth (Ishtar / Ashtar) - Kuzuryu - YHVH|
|Locations||Tokyo Millennium - Underworld - Expanse - Eden - Diamond Realm - River Styx|
|Terminology||Millennium Kingdom - Great Cataclysm - Order of Messiah - Ring of Gaea - Terminal - Sword fusion - Identification Program - Summon Doll - Seven Pillars of Solomon - Sabbath - Abaddon's Innards - Megiddo Arc|
|Content||Demons - Bosses - Skills - Items|