The action takes place in a fantasy world set in the entourage of the modern world and inhabited by magical animals. The geography of this world represents the Earth's continents with altered locations, but they are located in a huge lake, which is located on the Dark Continent, an incredibly huge and dangerous place. In this world, there is a certain organization of Hunters, who do all sorts of things, from treasure hunting and rare animal species to contract killings. Their license gives them many privileges - the ability to travel first class on various modes of transport for free, access to information that is not available to other people, and the right to take large sums of money from banks. Because of this, there are many people who want to become Hunters, so there is an annual exam in which the few who are truly worthy to be Hunters are chosen. A Hunter can receive three stars: one for special achievements in his field, a second for gaining an official position, and a third for special achievements in several fields. There are so-called Zodiacs, the twelve strongest Hunters, each bearing the title of an animal from the Chinese horoscope.
Hunters must be proficient in Nan , a technique for controlling their own aura, or life energy, which all living beings emit in small amounts. Professional hunters must know how to use Nan, so after the main exam, all those who pass it pass an additional exam. There are four basic techniques of nan:
Ten - allows you to trap the aura in the body.
Zetsu - allows you to hide the aura.
Ren - allows you to produce more aura than usual. Applying both Ten and Ren at the same time, you can produce a large amount of aura without letting it dissipate.
Hatsu is an aura control skill that allows you to use it to create different techniques. Each Nan user has his own Hatsu, different from the Hatsu of other Nan users.
There are a total of six types of Hatsu. Each Nan user may be predisposed to one of them, but he may also master techniques of other types, but they will not be as effective as the techniques of the type of Nan to which the user is predisposed. The predisposition to a certain kind of Hatsu is also determined by the character of the user. In order to determine whether a person belongs to one group or another, a certain test called water divination is performed. Pour clean water into a vessel and put a leaf of any plant on it. Then hands are brought to the vessel and the power of Wren is applied to it. Depending on the reaction of water or leaf is determined by the type of Hatsu to which the diviner is most prone.
Amplification allows the user to enhance their physical abilities. When guessing, the amount of water in the vessel increases. Amplifiers are usually simple and straightforward.
Highlighting - allows the Nen user to highlight their aura and attack with it. Water changes color when guessing. Highlighters are fiery and impatient.
Transformation - this ability changes the properties of the aura. The taste of water changes when guessing. Transformers are usually impermanent and sometimes deceptive.
Manipulation - allows the Nen user to control anything or anyone. A leaf on the water begins to ripple when guessing. Manipulators are distinguished by their intelligence and calm character.
Materialization - allows the Nan user to create objects. When divination, an object, such as crystals, is formed from water. Materializers are nervous, withdrawn and sometimes irritable.
Specialization - this type of ability is the hardest to master, but you can have an innate predisposition for it. Specialists have abilities that do not fit into any of the previous categories. In water divination, changes not listed above occur. Specialists are distinctive and independent.
To enhance their Nan, Nan users often come up with certain conditions, without which the ability cannot work. The stricter the restrictions imposed on the ability, the stronger it becomes.