Heart Purity (also known as purity of the heart) is the personality trait of some of the characters in the Dragon Ball franchise. It effectively means that the person is either pure good or pure evil, without any mixtures between the two, whatsoever. A character with this trait is said to be "pure of heart." This personality trait is a prerequisite to being able to use - and being resistant to - some techniques and abilities in the franchise.
There are two ways to be pure of heart: to be either pure good, or pure evil. It is significantly more difficult to be pure good than it is to be pure evil, as sinful pleasures (such as lust and greed) can surface in even relatively altruistic people.
It appears as if it is possible for sinful desires to be present and latent inside people, and those people will still be considered pure of heart, so long as they repress those sinful desires. This is suggested when Krillin could not ride the flying nimbus (which, as we will see below, is one way of testing for heart purity), but later in the manga, was able to throw a spirit bomb (another means of testing for heart purity). Babidi has seen to control Demons, People, and Saiyans if they are evil.
Examples of negative feelings that can cause a person to not be pure good are:
- Lust. The desire for sex. This is the first negative thought seen in the franchise, as it is shown as the reason Master Roshi is unable to ride the Flying Nimbus.
- Greed. The desire for material wealth. Bulma is shown to have this trait. Yamcha is later shown to possess this trait.
- Selfishness. This is another trait that Bulma has.
- Aggression. The tendency to be easily provoked into violence, often beyond what the situation calls for. Many reformed villains (especially Piccolo and Vegeta) are shown to have this trait.
- Sadism. Possibly the most evil trait of all, the one demonstrated by most of the villains of the franchise. This is the desire to inflict pain and suffering on innocents, simply for the sake of inflicting pain and suffering. Those in the franchise believed to be pure evil almost always demonstrate this trait, and it appears to be their most prevalent. They often prefer to drag their victim's deaths out as slowly and painfully as possible, and also seem to enjoy mental torture prior to their victims' demise (as seen when King Piccolo said he would only destroy one sector at a time so the world would live in fear, or Cell wanting to give the people of Earth ten days to live in fear while they await the Cell Games).
Things that are affected by Heart Purity
The following things require either the user to be pure of heart to use the technique, or require the opponent to be pure of heart to resist it. These are listed in the order they are discovered in the manga.
Various Flying Nimbus clouds exist in the Dragon Ball universe, most of which are owned by Korin. These are quasi-sentient beings who come to their masters simply by their masters calling for them, and are used as personal aviation for their masters. However, they only allow masters who are pure of heart to ride them.
It is unknown if a person who is pure evil could ride a flying nimbus, as no pure evil character is ever seen attempting to do so.
Korin has the ability to read minds. Although purity of heart is not necessary for this power to work, he exposits, the first time he is seen using it, that purity of heart certainly makes the task easier (comparing it to looking through transparent glass).
The Devilmite Beam (the signature technique of Spike the Devil Man) amplifies an opponent's negative thoughts until the victim's heart literally explodes. However, this requires a person to have at least a single negative thought, so only those who are pure good can resist it. As the power of the technique is based on the evil within the victim's heart, this technique is implied to be extremely lethal when used on those who are pure evil.
In Dragon Ball Fusions, this immunity is represented by a passive Skill called Pure Heart which nullifies the effects of both the Devilmite Beam and Psidevilmite Beam. It appears as one of Kid Goku's Skills, referencing his immunity to the Devilmite Beam in the main series.
Interestingly, Goku Black and Zamasu also possesses Pure Heart as one of their passive skills in Dragon Ball Fusions, despite their evil actions. However should be noted that while their actions and methods are evil (from killing his master in cold blood, stealing Goku's body and murdering Goku's family, to genocide of both gods and mortals as part of the Zero Mortals Plan) their motives are the result of Zamasu's strongly held belief that mortals are evil and thus from Zamasu point of view his actions are completely justified. It should be noted that Gowasu noted that Zamasu was so well-balanced when he would brew tea, implying that Zamasu (and by extension Goku Black) is a pure hearted and just man, driven to extremes by his beliefs concerning mortals whom he views as the gods' greatest mistake.
It should be noted that while Goku possesses a pure heart, he has killed people though most were villains who gave Goku little choice but to kill them (such as Frieza and Kid Buu), with the exception of Grandpa Gohan whom Goku killed unintentionally while in his Great Ape form (Goku was shown to be remorseful after realizing he was responsible for his adoptive grandfather's death during his battle with Great Ape Vegeta during the Saiyan conflict) due to his inability to control himself in that form. This shows that one can commit potentially evil actions (such as killing) yet still be considered Pure Good as long as their intentions for doing so are good or lack any negative intent (such as in Goku's accidental killing of Grandpa Gohan).
As the Devilmite Beam causes evil thoughts to explode, it is possible that one must be aware that such thoughts are evil or negative (similar to how Innocent Buu was unaware that killing people was wrong before befriending Mr. Satan) for them to be effected, thus explaining Goku Black/Zamasu's immunity as Goku Black/Zamasu believes his extreme methods are completely justified.
Spirit Bombs can only be created by those who are pure of heart. Anyone who is tainted by any negative thoughts would instead have the gathered energy absorbed into their body (which can in fact be used to the warrior's advantage, as seen Dragon Ball Z: Super Android 13!).
Furthermore, a spirit bomb created by one of the two types of pure-hearted warriors (either pure good or pure evil) will not hurt anyone else of similar alignment. This means that a spirit bomb created by a pure good warrior (such as Goku) will not harm a pure good warrior (such as Gohan).
In several video games, evil characters such as Cell & Mira are shown to be capable of using the Spirit Bomb, however this is due to the fact that both of these characters are pure evil. In fact Mira uses a Spirit Bomb created from the energy of his soldiers to destroy New Namek, an act which confirms that pure evil characters are capable of using the Spirit Bomb. However most games ignore character alignment (save for certain techniques like the Fusion Spirit Bomb where it plays an important role) allow the technique to damage opponents regardless of their alignment.
It is theorized by Tien Shinhan that one can only become a Super Saiyan if they are pure of heart. This, however, is refuted when various non-pure characters (including Vegeta) are shown being able to achieve the form. However it should be noted that Vegeta himself theorized that a Saiyan could be pure evil in order to attain the form (and even believed that he himself was pure evil when he obtained this form).