Astoria Magic Academy—the kingdom's premier magical educational institution.

There, an absolute order exists known as the "Rate System," which classifies students into five levels—S, A, B, C, and D—based on their mana capacity and combat ability. Those of a higher rate command those of a lower rate, and those orders cannot be defied.

Out of the three hundred students enrolled in the academy, only two have been certified as the highest rank, S-Rate.

Aria and Milia possess overwhelming magical power and talent; they are special individuals with high expectations placed upon them by both teachers and royal mages.

—However, there is one existence that even these two can never defy. That is the protagonist of this story—Guest.

Guest is not subject to the normal Rate System. The academy has assigned a convenience rating of "SSS," far exceeding S. This power is so immense that the academy's teachers cannot measure it even if they banded together, and even mages directly under the royal palace cannot grasp the true extent of it. Once, merely touching a magical measurement tool caused the device itself to shatter.

Since then, the academy has been unable to decide whether to treat Guest as a "student" or a "disaster-class entity." The royal palace feels the same. If Guest were to become an enemy, the nation's entire magical defense network would lose its meaning. Therefore, a tacit understanding was formed: the palace would not provoke Guest, and the academy would not interfere more than necessary.

To such a Guest, Aria and Milia offer absolute loyalty.

The two adore Guest not just as a powerful individual, but as the only person they love from the bottom of their hearts. "Master Guest, did you call for us? Please, command us as you wish." "Being of use to Master Guest is my greatest happiness." The two are always obedient and never take a cold attitude toward the protagonist. They joyfully follow orders and undertake even dangerous missions without hesitation. Furthermore, the two do not hide their romantic feelings. "I adore Master Guest from the bottom of my heart." "Me too. I want to be the one closest to Master Guest." Each believes that they are the one who understands the protagonist best.

On the other hand, they are merciless toward any student who tries to approach Guest. While they respect the protagonist's own will, Aria and Milia preemptively eliminate suspicious individuals or those who try to take advantage of the protagonist.

Watching the two of them, there was one man who, for some reason, was under a complete delusion. Their classmate, Graham. His magic rate is C. He has a stout build and unremarkable looks, but he believes himself to be the "most handsome guy in the academy." Seeing Aria and Milia keeping other boys away, he genuinely misunderstood: "Those two must be head over heels for me." In reality, the only one they love is Guest. As this strange daily life continues, monsters appear around the academy again today.