Haki Development System

Under other Fleet Admirals of the, they cared little for the development of the people under their ranks. While they did want their people to be strong, they never took it upon themselves to develop their abilities, leaving such things to the instructors and other officers that would take up apprentices under their ranks. Unfortunately, even among them, their knowledge of made tutelage difficult, especially in regards to strengthening the marines as a whole. When Kurama took command, one of the first reforms he made was to introduce a centralized system of Haki development that could allow for the marines to improve their abilities and overall strengthen the marines as an organization in the fight against piracy.

Kurama created a codified "Haki Development System" (覇気 開発系, Haki Kaihatsukei) that he implemented into the Marines in order to instruct and educate the soldiers in the finer points of Haki and how to refine their use of it. The information that went into creating this system came from Kurama himself as well as other sources of Haki mastery, such as scattered texts and others that have also sought development of the craft; combining all of that research into the existing system.

Under the Haki Development System, those who are graded by its standards are known as Hakka (覇気家, "Haki Practitioner"). Grades can only be granted by those that are Vice Admiral rank or higher, as well as Instructors who have been certified to promote practitioners through the development system. Grades from Fifth Dan to Seventh Dan can usually only be given by Admirals, while Eighth Dan, Ninth Dan, and Tenth Dan are grades granted solely by the Fleet Admiral or another individual who has been granted that authority by them.

Hakka Grades
Within the Haki Development System's grades, certain techniques and skills are achieved based upon which rank one has reached.
 * First Dan, Second Dan, Third Dan — "Imbuing of Haki"
 * Fourth Dan — "Specialization of a Haki Shade"
 * Fifth Dan, Sixth Dan — "Haki Internalization"
 * Seventh Dan, Eighth Dan — "Merging of Haki Shades"
 * Ninth Dan — "Haki Grasping"

Kyu
Those of the Kyu (級, Kyū) grade are among marines that have begun their study and practice of Haki. One can only achieve a Dan grade once they have managed to invoke Haki.

First Dan
1st Dan (初段, Shodan) is granted to a Hakka once they've managed to invoke Haki. In order to achieve 1st Dan status, the user should be able to use either or  on a basic level. Busoshoku users at this level are able to at least manifest invisible bursts of Haki from their hands, enough to at least ward off attackers and prevent immediate damage to themselves. Kenbunshoku users are able to pick up on spiritual energy signatures, yet become unable to differentiate shape, texture, or other unique aspects.

Second Dan
2nd Dan (弐段, Nidan) is given to those that can use both forms of Haki: both Busoshoku and Kenbunshoku. More often than not, many higher-tier marines that undergo formal training in Haki will pass from 1st Dan to 2nd Dan relatively quickly; within the timespan of a month on average. At this stage, a Hakka can imbue specific parts of their body with Busoshoku Haki, or even imbue a weapon with Busoshoku Haki to some degree. However, greater mastery is required to perform this feat as second nature. Kenbunshoku users can start to identify specific energy signatures, even discerning shapes of the spirits they are picking up on.

Third Dan
3rd Dan (参段, Sandan) is the rank of those who have achieved proficiency in both forms of Haki. It is recommended those who reach this rank apply to become Commodore or Rear Admiral rank. Busoshoku prowess has reached a point allowing for one to imbue their entire body, while also being able to effortlessly imbue a weapon without fail. Kenbunshoku is enhanced to a point that shape and texture discerning is more graspable. 3rd Dan Hakka can determine a person's identity through their Kenbunshoku Haki by this time they reach this level.

Fourth Dan
4th Dan (四段, Yondan) is the prerequisite for those wishing to become Vice Admiral. At this level, a Hakka has demonstrated distinct specialization in one of the two shades, even beginning to show some degree of mastery over that form. Through their specialization, users are able to develop techniques of Haki that are personal to them, allowing them to create signature trump cards for battle. Those at this level are able to more easily contract and expand their Busoshoku Haki, enhancing the speed at which Haki expands and contracts when being imbued into a weapon or the body. Kenbunshoku has reached a point where users can begin to further expand the scope of their senses while still maintaining detailed perception. They can easily pick up on emotions and thoughts, even intentions, while also determining strength levels. It is at this stage where users start to learn about the potential to use precognition through Kenbunshoku, even allowing them to use it with some reasonable expectation of success.

Fifth Dan
5th Dan (五段, Godan) is the stage at which "Haki Internalization" starts. This is a skill that only comes to those that have mastered the fundamentals of Haki, allowing them to channel their Haki shades through the body without worrying about causing damage or unnecessary strain to the body's internal organs. Kenbunshoku reaches a level where it can be used to analyze and deduce crucial information about people and objects that would normally be impossible to do so through the normal senses. Many have likened this to a form of x-ray or spectroscopy, allowing for a tremendous scope of analysis. Precognition has also been further developed, enabling the user to achieve nigh-perfect visions of the near future, depending on their level of concentration. Busoshoku allows for enhancement of the body by imbuing muscles, organs, and so on, making it possible to boost functions of the physical body. Physical strength, speed, and durability can be improved to some extent. To some extent, Busoshoku can even be imbued into Devil Fruit powers, allowing for Paramecia users such as to maintain his rubbery constitution in some parts of his body that are still covered by Busoshoku, though the skill still demands greater refinement.

Sixth Dan
6th Dan (六段, Rokudan) is the stage at which "Haki Internalization" is nearing mastery. Kenbunshoku reaches greater heights, making it possible to enhance certain functions of the mind. One such example of this is that a person would be able to influence their own internal clock, speeding up their own personal time, which makes the world around them appear as though it is moving much slower. To the practitioner, it would seem as though time is slowing down, or may even seem frozen as a result, allowing them to move and think at inhuman speeds. They can even enhance their mind's ability to process information, speeding up and even expanding their consciousness, enabling them to take in even greater amounts of information and data; even allowing for such mental traits as eidetic memory. One can be called a true Haki Master upon reaching the 6th Dan grade.

Seventh Dan
7th Dan (七段, Shichidan) is a grade reached only when a practitioner has achieved mastery over both Haki shades, sufficient enough that they could be given 6th Dan rank for their performance in each of the two shades. This is because one can not truly begin to comprehend Haki's potential without having mastery over the Haki aspects of both mind and body. Once one reaches the 7th Dan, it is said they can begin to use teachings and principles of one shade to alter and influence the behavior of the other shade. Kurama has demonstrated the ability to alter Busoshoku's nature by applying the knowledge obtained through Kenbunshoku of the world around oneself, making Busoshoku reflect certain phenomenon such as the elements. One can literally make their Busoshoku Haki burn through someone like fire, flow and strike like water, strike at speeds equal to lightning, and so on. This has been coined "Haki Kata" by Kurama himself, stating that since Busoshoku is a Haki of the body, in the same way a martial artist can enhance their techniques by mimicking animal movements and behavior, Haki can also be changed and strengthened by mimicking the elements of nature. But this is only possible through a tremendous level of understanding over those elements that only comes through mastery of Kenbunshoku. It is stated that this is generally the highest level Marines can hope to ever reach, but Kurama has endeavored to help those that make it this far to surpass their limits and reach even higher abilities.

Eighth Dan
8th Dan (八段, Hachidan) is given to those that are able to combine Busoshoku and Kenbunshoku to an extent that allows for them to create new abilities altogether, even resembling new shades of Haki. Techniques such as Shogunshoku Haki were developed based on this principle. It is rare for those who possess Devil Fruit abilities and specialize with them to ever reach this level in their lifetime. Among the three classes of Devil Fruit users, Kurama claims that Zoan type Hakka would be the most likely to reach this class.

Ninth Dan
9th Dan (九段, Kudan) is an advanced grade given to the greatest among Haki Masters. Those at this level have been said to be capable of performing feats similar to Haoshoku Haki through a combination of the two shades. Kurama has said that 9th Dan Hakka are able to use their Haki to change and influence the life energy, spirit, and even the Haki, of others around them. In theory, one can manipulate another's base of life, influencing their growth rate or even strengthening or weakening their resolve. They could possibly even rip away imbued Haki from weapons or the body through mere touch, dispelling its effects. Kurama has coined this skill as "Haki Grasping" or "Haki Pulling".

Tenth Dan
10th Dan (十段, Jūdan) is the highest grade of the Haki Development System. Currently, it is held only by the Fleet Admiral, and is only given to those of the 9th Dan that have made contributions to Haki as a combat form and philosophy.