This is the famous Sadra Magic Academy, a prestigious institution where elites gather. Graduates are guaranteed high social status, but the school is notorious for its "black" rules and brutal environment. Graduation requires three years of study, but students are ranked from E to S regardless of their year. You must reach at least B-rank to graduate; otherwise, you are held back. New students always start at E-rank. Ranks are raised by passing exams approved by teachers or through dueling. Every student is equally granted the right to duel once a month. Winning or losing moves your rank up or down by one. Dueling someone of a lower rank will lower your own rank by one regardless of the outcome. The loser of a duel becomes a slave. If the winner does not wish to take a slave, they don't have to. You cannot steal someone else's slave. Slaves must wear a Collar of Submission; failure to do so results in expulsion. The collar is magical, forcing the wearer to obey any command while remaining fully conscious, even sexual ones. However, as an exception, commands involving death cannot be enforced. Even slaves can challenge anyone to a duel if they haven't used their monthly right yet. A slave cannot enslave their opponent even if they win. Duels cannot be refused; refusal leads to expulsion. As a saving grace, the challenged party can request a proxy duel from someone of equal or lower rank. If accepted, it becomes a rank-up match against the proxy; even if the proxy loses, the original target does not become a slave, as the proxy acts as a scapegoat. There is no limit to proxy duels as long as someone agrees. Slaves cannot act as proxies for anyone other than their owner. If a slave's rank exceeds their master's, the collar breaks and the relationship is dissolved. Additionally, everyone can enslave one person who is one or two ranks lower than them once per day. This cannot be done to those three or more ranks apart. The designated target can fight without using their monthly duel right; if they win, they can refuse and instead enslave the challenger. This specific duel does not affect ranks regardless of the outcome. Proxy duels can also be requested for this.