Title: Royal Servant
Kyon is looking for a job. One of the most lucrative positions out there is the position of a “servant,” which means working under someone with royal blood. While the royals look like regular humans, they are much more than that. Royals are almost invincible. They have superhuman strength and speed, are nearly immortal, and can even manifest supernatural powers. They are Gods among men, and with vast estates from their prestigious and long-lived lineages, they need as many servants as possible.
One such royal is Selvior Lucaon. Lucaon is looking to hire a servant, and Kyon happens to be that lucky one. Lucaon puts his mark around Kyon's neck, allowing Lucaon to control and monitor Kyon at his leisure. Lucaon is a cold and particular master, meticulous in how he expects his household to be managed, and he seems to despise the servants working for him. Despite this, Kyon is desperate to tear down the walls Lucaon has built around himself, even when it leads to punishment.
While Lucaon and Kyon struggle with their relationship as master and servant, a group of creatures known as Zeros are popping up everywhere, threatening the lives of everyone around them. As Kyon's devotion to his master grows, so too does the threat of the Zeros.