Breeding mission | U-Olga Marie

Lostbelt: As opposed to the Proper Human History, the history of "winners" born from correct choices and proper prosperities leading to the "present", the history of "losers" born from the wrong choices and mistaken prosperity is cut off. Considered "unnecessary" and cut off from becoming even parallel worlds, this history which has hit a dead end is known as a Lostbelt. If one thinks of Human History as one long scroll, the Lostbelts are like another scroll entirely that was discarded once it was clear it was no longer useful.

Singularities are unobservable regions that do not exist within Chaldea's recorded history. It's as if a hole has opened up within the timeline, a hole that is separate from the regular temporal axis. If Human History is thought of as one long scroll, Singularities are like stains that weaken the scroll by contaminating the history around them.

Under ordinary circumstances, a Master is always a spellcaster, usually a Magus with a Magic Circuit, who is selected by the Holy Grail. It is possible for an ordinary person to become a Master, An active Master will also possess a Command Spell somewhere on their bodies as a visible proof of their contract, the role of a master is to command their servants and supply magical energy to them

Servants are Spirits made into special Familiars of the highest rank, referred to as Ghost Liners by the Mage's Association, that are bound to the Master. Typically Heroic Spirits under most systems, they can also sometimes be Divine Spirits, Phantoms, Wraiths, and living people depending on various circumstances.

Chaldea is a secret agency founded with the purpose of preventing the "certain extinction" of the human race. It specializes in handling temporal anomalies and other existential threats to humanity. The hidden purpose of the organization is the enaction of the Human Order Revision Incident by CHALDEAS in following Marisbury Animusphere's Grand Order.

command spell: Unable to normally be controlled by humans, they are burdened by the "absolute condition for materialization", the authority of the Command Spell carved into them at the moment of summoning. They are holy marks signifying a Magi's status as a Master. Masters must take careful consideration of the usage of Command Spells, because they can be indispensable as both an emergency measure and method of governing the Servant. Depending on the relationship, they are the only thing keeping a Servant bound to them, while others will stay by their Master even without them, and those like powerful Berserkers cannot be ordered without them. Some Servants will become more antagonistic towards their Master should they attempt to bind them, so they pay careful consideration before using them. It is normal that a Master has general control of their Servant even outside of the Command Spells due to them being the anchor that ties them to the world with their Magical Energy. Command Spells require no incantation unlike normal spells, and the Master only needs to put their mind to it and order the Servant. Imagining the shape of the Command Spell and giving the order as they release it is enough to activate it. The proximity does not matter, allowing for it to take effect even if the Servant is miles away or through a Bounded Field advanced enough to cut off all other communication. It can be performed unconsciously if the command is direct enough, but will not be used if they are not serious about the Command. They are three absolute orders of unconditional obedience that can either restrain or reinforce the action of a Servant. Command Spells can force Servants to do anything possible for them, even committing suicide. The strength of the command depends on the Master, directness of the order, and the amount of energy it requires. Those that are broad and long lasting will weaken the power of the Command Spell.