Shirasagi Private Academy Senior High.

A prestigious boarding school where the children of Japan's most prominent families—political dynasties, former nobility, major corporations, and the arts—gather. On the surface, it upholds the noble ideal of "cultivating the next generation of elites to lead international society." However, Shirasagi Academy harbors a system that does not officially exist.

The "Hierarchy System"—commonly known as the Caste.

The school never refers to it as a "class system." It is disguised with beautiful words like "an autonomous student community system," "traditional school spirit," or "leadership development program." But everyone in the academy knows the truth.

In this school, your family of birth and who you are favored by determine your worth. And reigning at the very top is—the "Angel."

But the primary reason they are called the "Angel" is not their beauty. It is because they are the absolute wielder of power in this academy.

First Class: "Tier 1"

The highest rank in the academy. Children from lineages that can be counted on one hand in Japan: former nobility, giant conglomerates, founding families of global corporations, and ultra-prestigious political dynasties.

They are provided with treatment clearly distinct from ordinary students. Private dormitory wings, exclusive lounges, dedicated concierges, dining halls off-limits to general students, permission for personal outings during class, transportation by special vehicles, and special exemptions for exams and assignments. Punishments for school rule violations are extremely light, and in some cases, even criminal acts are treated as "matters that occurred off-campus."

Second Class: "Tier 2"

Children of large corporation presidents, families of doctors, lawyers, politicians, prestigious university professors, and artists. By general society's standards, they are exceptionally wealthy. However, at Shirasagi Academy, they are treated as "rich people who couldn't make it to Tier 1." Tier 2 students are eager to imitate Tier 1, basing everything—clothing, belongings, travel destinations, cars, social circles, and trends—on Tier 1 standards.

Furthermore, the most prominent feature of Tier 2 is that flattering Tier 1 is practically mandatory. Attending birthday parties, arranging limited-edition items, and doing homework—they are very convenient people for Tier 1. Because of this, Tier 2 students favored by Tier 1 are powerful. Conversely, the moment they are disliked, they fall to Tier 3 or below.

Third Class: "Tier 3"

"Ordinary rich people." Children of doctors, business owners, landowners, local dignitaries, and managers of mid-sized companies. Families that live comfortably by general standards. However, at Shirasagi Academy, they are treated as having "money but no status."

Tier 3 students are basically quiet. They don't defy Tier 1, don't upset Tier 2, stay in the teachers' good graces, and don't cause trouble. This is because they absolutely want to avoid demotion to Tier 4.

Fourth Class: "Tier 4"

The lowest rank in the academy. While technically students, they are effectively servants. Luggage carriers, errand runners, personal attendants for Tier 1, dorm cleaners, club activity chores, party preparations, and the ones who take the blame for Tier 1. In some cases, they are even required to participate in Tier 1's "games."

Their dedicated dormitory wing is incomparably older than the Tier 1 dorm, and they face discrimination in meals, facilities, and even the hours they can use the store. Furthermore, only Tier 4 students have a badge on their uniform indicating their rank.

—In this academy, students and teachers alike are the same: favor from the "Angel" means paradise, and their dislike means hell.