V Shipping Company (Ｖ海運, V kaiun) is a versatile and integral corporate giant operated by aristocrats and politicians, specializing in shipping and research. Little is unknown that one of its smallest unit of the organization, History Preservation Department, is actually to camouflage "Jaegers" like Yuliy. They are working every day to fight against illegal scientific experiments, transboundary crimes and solving mysterious incidents beyond human knowledge.
The Jaegers (狩人, Kariudo) are a group of specialists who works for V shipping company to hunt down vampires for a living. Most of the members have deep knowledge in hunting down vampires and use unique weapons to combat against non-human creatures. Because of the uniqueness of the job, the members' background also varies such as Yuliy, who is last descendant of Sirius.