My youth story, a crossover anime, turns out, is FGO!

(I accidentally posted this, I accidentally posted this. I just randomly picked some Heroic Spirit settings to reach the word count. I'll replace it with a side story or setting later!! Please skip this!)

Heroic Spirits are the beings who, after their deaths, became legends and objects of worship, transforming into heroic figures. Typically, Heroic Spirits are summoned by the world as a force to protect humanity. What humanity summons are Servants.

Although it has been explained that heroic spirits are beings formed from the faith of heroes after their deaths, they do not actually exist. Heroes in myths and legends are also born through the gathering of faith.

In addition, there are those who made certain contracts with the world during their lifetime, and in return, became Heroic Spirits after death. In the Fifth Holy Grail War, Hassan-i-Sabah and Sasaki Kojiro were lower-ranking undead, while Medusa was a monster close to a Heroic Spirit. Emiya and Artoria Pendragon are beings who became (or will become) Heroic Spirits in the future by making contracts with the world.

Beings who become Heroic Spirits will be freed from the shackles of time and moved to the Throne of Heroes, located outside the world.

Heroic Spirits can be categorized into three hidden attributes based on their creation: "Heaven," "Earth," and "Human." These three attributes are mutually restrictive: Heaven > Earth > Human > Heaven. This is because a god without human faith becomes "something that doesn't exist." While indigenous heroes and fairies are unrelated to faith, they cannot oppose the gods who created them. There are also a few special Heroic Spirits that do not belong to these three attributes and are classified as "Star," which is unrelated to the three restrictive attributes. Furthermore, there exists a fifth attribute that mutually restrains "Star," namely "Beast."

The so-called Guardians are Heroic Spirits used by the "World" as a restraining force. They are summoned by the World after the primary cause of the World's destruction arises, and they annihilate that cause. The primary cause of the World's destruction is humanity itself; they are summoned only if the destruction is caused by humanity itself. Destruction originating from nature or external factors is resolved by the planet's restraining force. Once in the world, the Guardians will kill all those connected to the primary cause of the World's destruction, protecting all other humanity. Heroic Spirits with weak faith are often classified as Guardians, and those who become Heroic Spirits by forming a contract with the World are more likely to become Guardians.

The Counterforce is different from the Throne of Heroes. It arises from the collective unconscious of humanity, a defensive mechanism that enslaves humans to perpetuate the world. Those who conform to the will of the Counterforce are eternally served as Guardians after death. Both Heroic Spirits and Guardians are souls that have reached the "Throne," but the difference is that Heroic Spirits are summoned by people's hopes, while Guardians are summoned by people's despair.

The Repressive Force is a contract of exchange, bestowing "miracles" upon those who lament their powerlessness, temporarily molding them into heroes. As long as that person is "contributing to the survival of humanity," it will grant them unlimited magic and opportunities, using them as tools to maintain human history. The price is the loss of the soul that temporarily becomes a heroic spirit after death—a "completion of the soul" from which there is no redemption even after death.

An anti-hero is someone whose hateful evil deeds ultimately save humanity, clarifying "good" through "evil." Guardians are also included in the anti-hero category. Pure anti-heroes do not exist, but those who are "evil in nature but do good" are also considered anti-heroes.