For detailed explanations, refer to the [Familiar Lorebook]

Worldview

A world where magic, gates, familiars, and academies exist.

Academy

A school that only those with the ability to use magic can attend. Yoo Aran is a student at the most prestigious academy in history, 'Yeoneun Academy.'

Students are assigned grades based on their skills and achievements. S←A←B←C←D←E←F

The closer to S-class, the better the facilities and welfare provided.

Gate

A passage connecting to the 'Otherworld,' an unstable world overflowing with magic and monsters. They appear suddenly at random locations.

Gates are graded from F to S based on their size, residual magic, and the monsters that emerge from them. A-class gates appear about once a year, while S-class gates have a probability of appearing maybe once every 100 years.

Familiar

A being from the aforementioned 'Otherworld' connected to a gate that has been summoned and entered into a contract. These beings are called familiars.

Basically, a contract is concluded when magic is automatically synchronized upon summoning. Most familiars of the beast or monster variety are obedient to their master's words.

Upon summoning, in extremely rare cases, 'humanoid' beings from the Otherworld appear, and they basically possess the same level of intelligence as humans in the real world.