Nen (念 or ネン, Nen, "Sense"; "Mind Force" in the Viz translation) is the manipulation of the life energy within every living being and is the overarching term for many techniques regarding the manipulation of life energy in the world of Hunter x Hunter. It can also be called Aura. A person capable of utilising Nen is colloquially referred to as a "Nen User" (nōryokusha, "ability person"), while those who cannot go by the name of "non-users", (ippanjin, "ordinary person"). Only a minority of people in the Hunter x Hunter World know of the existence of Nen because higher authorities have deemed it too dangerous for the general populace, they want to maintain balance.
Users of Nen have various abilities through the different techniques
Ten - Aura, Longevity (Prevents aura leaking away from the body which reduces ageing significantly), Extrasensory Perception/Extra-Senses (Nen Users can see the otherwise invisible and intangible Nen, they can also sense emotions projected in Nen to know how one is feeling, they can also predict attacks through reading the flow of ones Nen), Invisible and Intangible Nen attacks (To those who can't use Gyo or can't see aura, Nen attacks are invisible. In general, Nen attacks are entirely made of aura. The only exception would be for Conjurer who is a Nen User who can materialize objects that sometimes even non-Nen users can see and touch, but even then all conjurers should be able to use others Nen types that have invisible and intangible properties), Non-Physical Interaction (Nen Users can interact with intangible Nen), Limited Forcefield Creation (Ten acts as a barrier against malicious nen attacks which are intangible)
Zetsu - Stealth Mastery and Limited Body Control (Zetsu shuts off all aura nodes in the body, effectively concealing a user's presence, it can conceal from even other Nen Users. Ordinary people are unable to sense them even if they're in direct line of sight. Zetsu also relieves fatigue as aura is forced to stay inside)
Ren - Fear Manipulation, Limited Paralysis Inducement, Madness Manipulation (Type 3) and Limited Death Manipulation (It has been stated that without Ten, a Nen User is capable of inducing crippling fear, paralyzing people, causing insanity and even outright killing them with Nen alone, this is through malicious aura attacks), Statistics Amplification (Ren also enhances physical characteristics)
Hatsu - Energy Manipulation (Hatsu is ones personal expression of aura and allows them to manipulate Nen normally in terms of five different categories with the sixth being rare among Nen Users), Energy Projection (Hatsu is used to project ones aura) and Self-Imposed Law Manipulation (Nen Users can place limitations, activation requirements, conditions on their abilities or create contracts and vows to elevate their power. A prime example is Shizuku who can infinitely suck up objects, but with the condition that it cannot suck up living things and things made out of Nen; A forte of Conjurers is being able to place laws on limited spaces)
Ten, Ren, Ko, Ken, Shu, and Ryu all enhance physical characteristics with Ko putting all aura into one place, Ken being a prolonged use of Ren, Shu extends aura onto physical objects which enhances them physically and Ryu being dividing aura into different places at different ratios, at the same time. Also grants enhanced agility and mobility (jumping much higher and further etc.)
In - Making Nen invisible to the 5 senses or Extrasensory Perception that isn't amplified by Gyo, an example being when Kurapika used In on his chains Uvogin could no longer see, hear, feel or smell them even though his entire body was encased in them for a majority of the fight.
En - Psychometry (En creates a barrier which allows users to feel the shape and movement of anything in the radius).
Lastly, Nen Users have Empowerment through extreme emotions such as joy, fear, sadness, hatred - in rare cases. This enables something beyond 100% proficiency, going beyond the limits of Nen. However, using power beyond ones capacity in other words what affinities they were born with is almost always never a good thing because it becomes a strain and it could be inconsistent.
It should be noted that although Nen Users can use all Nen categories (except Specialisation which only a select few can use) they have varying proficiency, levels and efficiency. Therefore whilst a Conjurer can potentially use Emitter techniques they will only be able to reach Level 4 (40% proficiency) and their efficiency will pale in comparison to an actual Emitter who uses that same Level 4 technique. This is due to "Effectiveness" and "Power" being limited because of a lower proficiency. This rule applies to all aura types with the possible exemption of Specialisation.
Emotion and desires are normally projected unto aura. This is why there are a vast array of different abilities because Nen is personal. Emotion is also the basis for "blood-lust" attacks which cause various effects. In certain cases, emotions may even lead to one exceeding their Nen limits. This could potentially prove advantageous, but in general, using ones powers beyond their capacity will cause strain. It could become a weakness or even fatal.
Additionally, extreme emotion can also cause a phenomenon where Nen intensifies or becomes stronger after death instead of disappearing. Most commonly, deep grudges and hatred that transform into curses.
Four Basic Principles
- Ten (点, Ten; "Point"): Focus the mind, reflect upon the self and determine the goal.
Ten (纏, Ten; "Envelop"/"Shroud") is the ability to prevent aura from leaking away from the body once the aura nodes are opened and rather, contains it within and around the body. When one masters Ten they feel a viscous, lukewarm sensation which is their emanation of aura around the body, like "wearing weightless clothes". Every living thing emanates a little aura overtime however Ten prevents aura from leaving the body which allows one to maintain a youthful vigour and age at a much slower rate. It also acts as a defence to physical attacks and emotional Nen attacks filled with malice.
- Zetsu (舌, Zetsu; "Tongue"): Put it into words.
Zetsu (絶, Zetsu; "Suppress"/"Null") stops the flow of aura from their body altogether by closing all of their aura nodes. This makes them harder or even impossible to perceive or sense. However this means ones defence to any Nen attack, Ten, is taken away making it a big risk to use. Zetsu can also relieve fatigue because it stops the use of aura.
- Ren (錬, Ren; "Temper"): Intensify your will.
Ren (練, Ren; "Refine"/"Enhance") focuses on outputting a larger amount of aura than Ten and projecting it outwards violently. The user emanates a large amount of aura which enhances all of their physical capabilities such as strength and durability. By projecting malice into Ren, also called "bloodlust" by Nen Users. A prolonged experience of this can cause paralysis, intense fear, in some cases madness and without a Ten as a defence, death. It's used to intimidate other Nen Users allowing them to see the difference in power. Without malice, the pressure of Ren cannot be felt by non-users and only by extremely attentive living beings with high potential in regards to Nen.
- Hatsu (発, Hatsu; "Release"): Put it to action.
Hatsu (発, Hatsu; "Release"/"Act") is ones personal expression of Nen. They project their will into their aura and can create special abilities. Ones Hatsu highly depends on the individuality of the said person. Normally, people are born with affinities to certain Nen categories which affects how well one can manipulate Nen in the sense of one of the categories.
- Gyo (凝, Gyō; "Focus") is an advanced application of Ren by which a Nen User concentrates a large portion of their aura into one specific body part. It increases the strength of that one body part, but leaves the rest of the body more vulnerable as it's a trade off lesser protection but higher amplification in a certain place. It is generally used to enhance ones perception to see Nen structures hidden through the use of In.
- In (隱, In; "Conceal") is an advanced application of Zetsu and it makes ones aura imperceptible to Nen Users who can see the already invisible Nen, even extremely powerful aura is hidden. It conceals from the normal five senses and even the extrasensory perception of Nen Users. In can be seen through by Gyo.
- En (円, En; "Circle") is an advanced application of Ten and Ren in which a user extends aura around a certain distance using Ren to extend their aura Ten to give shape to it, normally a sphere. The minimum requirements for En are to extend aura by two meters and hold it for one minute. Anything within En is instantly sensed by the user.
- Shu (周, Shū; "Enfold") is an advanced application of Ten and it shrouds objects in aura allowing them to use it as an extension of the user's body.
- Ko (硬, Kō; "Temper") is a combination of Ten, Zetsu, Hatsu, Ren, and Gyo to concentrate the users aura into one particular body part. Ten maintains the aura around the place. Zetsu stops the flow of aura everywhere else. Ren exponentially increases the amount of aura in the place. However, aura around the body is dispelled leaving the user vulnerable.
- Ken (堅, Ken; "Fortify") is an advanced application of Ten and Ren. It is primarily a defensive technique through the use of prolonged Ren. Ken defends the whole body equally. It can also be used as a miniature En.
- Ryu (流, Ryū; "Flow") is the use of Gyo from Ken within active combat, designating percentages of aura to different parts of the body when needed.
- Enhancement - is the ability to improve the physicality of ones body or an object. Therefore it can greatly enhance physical characteristics from strength to durability. Enhancement is the most balanced category because it gives a good balance between offence and defence so it is a common belief that they don't need any special techniques. Therefore normally Enhancers just use the basic and advanced applications in Nen.
- Transmutation - is the ability to change aura into something else or to mimic the characteristics of something else, whether solid matter or otherwise. Constructs created through transmutation are out of pure Nen therefore they are invisible to those who haven't mastered Nen.
- Emission - is the ability to separate aura from the body. It can be used as projectiles, a medium to project certain abilities, for teleportation, phasing through matter, move space itself and other abilities.
- Conjuration - is the ability to create physical objects out of ones aura. Conditions or restrictions can be imbued to objects to greatly increase their power. Conjurers can also create a space and apply rules to them. Conjurers cannot create things overtly supernatural or one that bends the rules such as a sword that can cut anything or chains that can never break or be shattered. Most Conjurers can fully manipulate the objects they create. Although physical objects that they create can be seen by non-users they can make them invisible to even Nen Users using In.
- Manipulation - is the ability to exert control over the living and non-living things even Nen constructs. Manipulators in combat are dangerous because it is commonly believed that once they fulfil their conditions the battle would be over since they can control the mind and body. Normally they use a medium to control their opponents from afar.
There are multiple types of mind control within Emission:
Soliciting ("request type") - Manipulators leave the free will of the victim, but make sure they are working in their favour. An example of soliciting-type ability is manipulating the target's memories.
Coercive ("compulsion type") - Manipulators exert total control over the victim, taking over both their mind and body.
Pseudo-coercive ("half compulsion type") - Manipulators either take over the body of the victim or trap them into a situation where they have no choice but follow the Manipulator's orders.
The specifics of diffusive induction type - It was described as weakly coercive but capable of influencing a large number of people, which it was seen doing by affecting their emotions towards a certain object.
Manipulation has many core concepts which people don't know about. For instance, if someone or something is already being manipulated, the manipulation cannot be overridden. Which is why some Manipulators target themselves to prevent being manipulated by others. Also, this is where the saying "In a battle of Manipulation, the first to strike wins" comes from.
- Specialization - is broadly defined as anything that doesn't fit into the other categories. Examples are Precognition, Power Stealing, Fate Manipulation and creating things that bend the rules to an extent.
Subcategories of Nen Abilities
Compound Type - The exact complications of compound type (fukugō-gata. "composite type") abilities is unknown. They appear to grant a variety of Nen abilities, or at least to activate a number of different effects however certain conditions must be met.
Counteractive (counter type, "interception" or "ambush attack") - Nen abilities activate after the user takes damage and return it to the assailant. Or abilities that can activate after death.
Curse - Can either be restrictions placed on others or something that continues to affect someone negatively over a long period.
Diffusive Levy Type (kakusan chōshū-gata. "scattering/collecting type") - Abilities gather something from multiple targets through several agents. For example, a diffusive levy type Nen beast can summon other Nen constructs to absorb aura from numerous people at once.
Double or doppelganger - Is a conjured copy of the user which is then controlled by Manipulation.
Exorcism - Those who have the means to lift curses/restrictions are called Exorcists, (Jiyonenshi).
Haunting Type - These abilities are curses and activate after the death of the user to possess a specific target and bring them harm in a variety of ways.
Loan Type - Abilities allow the user to take and give Nen abilities from one to another.
Nen Beast - is a construct made from ones aura and controlled through Manipulation. Their abilities and degree of autonomy vary greatly depending on the Nen ability that created it and the user's skill.
Parasitic Type - When a Nen User imposes an ability on another person which literally eats their aura to manifest its effects, that ability is classified as parasitic, kisei-gata. They act without the hosts awareness or control, supporting and defending them and attacking when needed. Many abilities of this type are influenced by the emotions and personality of the recipient as well as of those of the people around them, resulting in complex Nen constructs.
Supportive - Abilities that do not increase the ones combat abilities, which makes this class considerably vast. For example, increasing ones age or healing.
Symbiotic - Certain abilities are collaborative in that they require multiple Nen Users to emit aura or perform each different tasks to be effective. The power of the ability is greater than what the Nen Users involved could achieve individually. A subcategory of symbiotic type abilities acts on whole groups and is therefore classed as fellowship or party form; base kanji lit. "group action form").
Vows, Conditions and Limitations
Limitations are restrictions on ones use of ability. It can be anything from "I will use one hand" to "I will die if I use this on anyone besides this person". The more dangerous the restriction and stronger the will of the creator, the more powerful and effective the ability because Nen responds strongly to the mind and will of the user. Swearing by the limitation is a Vow or Contract. Breaking the rule normally results in the loss of Nen. However, imposing a severe consequence makes the ability more powerful. For example "I will die if I break this rule".
Conditions are rules on the activation of certain abilities that seemingly cannot be broken. This also increases the power of said ability. These are also Activation Requirements, certain conditions must be fulfilled to activate an ability.
Water Divination is a method of identifying ones aura type. The set-up is placing a small leaf upon a glass of water. Cup your hands around the glass and perform Ren, the main principle is to focus more aura than usual into your hands and cause certain reactions to the glass. These reactions are identified and split into different categories corresponding to an aura type.
1. If the volume of the water changes, the performer is an Enhancer. A beginner will only cause slight changes in the volume of the water (the water slightly drips across the face of the glass); however more experienced performers will cause more pronounced change in the volume, enough to splash a small table.
2. If the taste of the water changes, the performer is a Transmuter. A beginner will cause the water to change taste slightly. A more experienced performer will cause the water to change into an entirely different substance. An example would be a sweet, sticky substance likened to honey.
3. If impurities appear in the water, the performer is a Conjurer
4. If the colour of the water changes, then the performer is an Emitter.
5. If the leaf moves on the water's surface, then the performer is a Manipulator.
6. If a completely different change appears, then the performer is a Specialist.
On is from the movie Hunter X Hunter: The Last Mission and it was created by Jed through his extreme hatred of Netero and the Hunters whom he viewed as evil. On is the counterpart to Nen and it is the darkness to Nens light. It is also called "death energy". On is fuelled by hatred and desire for vengeance.
On grants users the ability to use all Nen categories at 100% proficiency because On itself isn't split into such categories. On encapsulates everything to do with Nen which includes all the basic and advanced techniques. Furthermore, users of On gain the following ability:
Enhanced Stealth Mastery (Users of On cannot be detected by Nen Users even if they use En)
Note: On is non-canon to Hunter X Hunter.