Hunter x Hunter is a popular shonen series first released in 1999 with an iconic 148-episode remake in 2011. The series introduced an adventure-filled world pioneered by hunters who utilize special energy called Nen for different reasons. Unlike most power systems in anime, Nen is broad, expansive, and complex to learn.

As a result of the power system's broadness, there are several techniques, principles, and styles an aspiring nen user must learn to fully grasp the Nen ability. As Hunter x Hunter may be getting a comeback anytime soon, a proper recap of how Nen fully works is necessary. A core part of Nen is the four principles of the technique: Ten, Zetsu, Ren & Hatsu. So, how does each principle work?

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Ten

gon and killua coated in nen

To master Nen, the four principles are essential. Wing first introduced these techniques in the Heavens Arena Arc to Gon and Killua. Later on, it was revealed that basic mastery of nen was a requirement to complete the Hunter exam. The major principles of Nen were among the first teachings of Wing.

The first thing to know about “Ten” is its elementary nature. Among the Nen principles, it is the most basic and the most important. The reason is Ten serves as the core foundation of nen techniques; however, it is not really useful in combat. Nen practitioners can learn Ten after their aura nodes are in prime condition. Nen essentially involves aura manipulation, so it’s only natural that the user’s aura nodes are in the best possible state. Consequently, Ten allows Nen users to accomplish this feat while maintaining their aura around themselves. In other words, Ten allows the free flow of Nen around the user’s body, forming a distinct aura that can only be seen by Nen users. Full mastery of Ten implies that no single aura leaks from a practitioner's body.

Contrary to other Nen techniques, Ten needs to be constantly maintained without breaks. While this may be challenging for newbies, it becomes as easy as breathing for experts. The technique helps reduce aging since the energy that normally leaks away from the body is kept within. It also allows Ten practitioners to shield themselves from basic, emotional Nen attacks. Summarily, it is a rudimentary principle that cannot be overlooked to use Nen expertly.

Zetsu

killua gon and their mentor using zetsu technique

Zetsu literally means "suppress/null," similar to its effects in the Nen power system. If Ten is the act of releasing aura, Zetsu is the complete opposite. It's the complete retention of Nen. Zetsu involves the complete closure of a Nen user's aura nodes to seal off any leaking energy from their bodies. This erases the user's presence from other Nen users since a robust“aura” is needed to detect if one is a Nen user or not.

Closing the aura nodes allows one to stalk or pursue other Nen users without their knowledge. However, to use Zetsu effectively, it needs to be timed perfectly. If the timing is off and one deactivates their aura using Zetsu, Nen users with acute senses will perceive the change, allowing them to be on their guard.

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Additionally, sealing the aura from one's eyes ironically heightens Nen users' ability to perceive the aura of others, even without seeing their aura. The Zetsu principle is ideal for Nen users like Killua, whose fighting style revolves around stalking and assassination. Zetsu can also be used as a form of fatigue relief since the complete withdrawal of one's aura reduces any form of exertion or tiredness.

Even though the Zetsu technique is formidable, it's not invincible. Using Zetsu makes one easily vulnerable to even basic Nen attacks, including emotional ones. Further, Nen users with heightened senses can perceive if they are being followed, easily rendering ineffective the Zetsu technique.

Ren

hisoka using bloodlust

Ren literally means "Refine/Enhance." The principle is the higher form of Ten and can only be achieved after one has a certain mastery of its application. Ten allows Nen practitioners to externally manifest their auras in a gentle manner. However. Ren involves the explosive aura outburst of one's Nen outwards. The outburst increases the strength and durability of Nen users as it’s a purely offensive technique. Furthermore, it serves as the groundwork for the execution of advanced Nen techniques such as Gyo, In & En.

Ren is much harder to master than Ten. According to Wing, it takes approximately one month to increase the duration of one's external manifestation of Ren in a non-combat space for more than 10 minutes. The required time for Nen mastery may be unpleasant; however, the rewards are fulfilling. When one reaches a certain level in Ren mastery, they gain the ability to infuse their Ren with animosity, creating “Bloodlust.”

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Bloodlust can paralyze targets, increasing their fear/dread even without Nen users using any form of physical attacks or movements on these targets. In addition, non-Nen users can sense the Bloodlust technique; however, they are unable to perceive the basic Ren. In the world of Hunter X Hunter, Ren is the physical proof of a Nen user's strength. It determines the rankings and sometimes prevents unnecessary fights.

Most of the offensive Nen techniques are a product of the Ren principle. So, considerable mastery of Ren signifies immense strength and formidable. Nen requires the constant furnishing and fine-tuning of one’s aura, so for users to be powerful, constant training is inescapable.

Hatsu

gon's janjanken

Hatsu, which translates as "Release/Act," is the most complex Nen principle. It differs for every Nen practitioner since it's a personal expression of the nature of one's Nen. Essentially, Hatsu allows Nen users to use their aura for a particular action exclusive to the user. It is influenced by the user's nature, among the six categories of Nen types, but is not restricted by it. In other words, Hatsu is an external manifestation of Nen users' exclusive ability, influenced by their nen category.

A perfect example of this is Gon’s Hatsu, “Jajanken.” This ability is mainly fueled by his nen category as an Enhancer. Also, he is the only person that can use the ability since he created it himself using his Nen traits. Consequently, Nen users can create their exclusive Hatsu after consistently training their Nen abilities. Nen principles set the framework for every Nen user; however, the power level every Nen user attains is largely dependent on their hard work, skill and talent.

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