Centuries ago, the Emperor felt the need to keep an eye on the ever-growing Naval Forces and, by Imperial decree, ordered a Kempeitai cell to be directly attached to the Naval Forces.
Being independent of the military hierarchy, the cell quickly became the eye of the Ministry of Defense for centuries to come.
Responsible before the Emperor of the Naval Forces loyalty, they were also actively gathering intelligence on the Warriors caste's members and were entitled to arrest and punish anyone suspected of treason.
The Tokkeitai have been disbanded with the foundation of the Republic of Kusari, however the organization quickly was reborn from its ashes following the return of the Emperor to the throne. Though, the official era of existence still ends in 819 A.S., the Tokkeitai continues their work until today. Acting as the eyes and ears of the Emperor, with loyalty sworn only to the Imperial Majesty and the Imperial Shogun. They appear as everyday members of the IAF, bearing their standard ranks but act as force in the shadows, executing orders in utmost discreetly without ever leaving a trail behind.
The original organization's methods have often been seen as despicable and immoral, its members being ready to go beyond ethical codes or military and civil laws to achieve their objectives. The unofficially recreated Tokkeitai is likely to depict even more extreme behavior.
Role
Members of the Tokkeitai are responsible for maintaining order among the troops and are often depicted as being cruel and merciless, even to comrades when they are suspected of treason.
Acting under the security doctrine of "Kikosaku", the Tokkeitai possess the competences to pursue "potential traitors and enemies of the Kusari state" - virtually enabling the arrest, interrogation, imprisonment or even extrajudicial killing of everyone without the requirement of an official warrant.
Internal Organization
Little was known about the Tokkeitai's internal organization. Their members were however known to never use ranks in operation, even if it's almost certain the organization had a hierarchy chain.
Tokkeitai members sometimes mentioned 'Trust circles', a particularity that made some speculate the Tokkeitai might be organized using small cells - councils made of half a dozen of agents at most - that were defined by a level of trust.
The emerging unofficial Tokkeitai's structure is entirely left unknown, given their very nature as "division of the invisible". The only known "fact" about the recreated Tokkeitai is a contact only known to the Kaigun Gensui: "Goryō"