Hakko Denshin Ryu Jujutsu (八光伝心流柔術. HDR, HDRJJ) is a school of jujutsu descended from and based on Hakko Ryu. The name means "Heart and Spirit (Soul) of Hakko-Ryu". In Japan, HDR is known as Kokodo (皇光道).
The school was founded by Yasuhiro Irie, Michael LaMonica and Antonio Garcia. Each was awarded their Sandaikichu grade from the founder of Hakko Ryu prior to leaving the Hakko Ryu organization. When setting up Hakko Denshin Ryu, each assumed the title of headmaster("Soke") of the new system in their respective geographical areas (Japan, US, Europe) and formed a federation called the Kokodo Renmei.
In the 1990s, A former Hakko-ryu Shihan and student of Yasuhiro Irie, Roy Hobbs, received Menkyo Kaiden (full teaching license) in Kokodo Jujutsu and, with Irie's permission, created a new Hakko-ryu offshoot, called Dentokan Jujutsu. 
Another Hakko Ryu offshoot called 'Hakko Densho Ryu' was founded by Palumbo in Colorado; this is unaffiliated with the other systems.
The philosophy can be summed up as "No challenge, No Resistance, No injury". This means that the practitioner should not start a fight, should seek every way reasonable to prevent a fight, and should strive to prevent injury to the assailant if a fight occurs. Injury is only condoned when "exceptional circumstances" exist (life threatening situations). The assailant is neutralized, and his will to fight is defeated through the use of pain compliance.
As a compliment to the painful techniques, the founder also integrated shiatsu into the art. Shiatsu is taught at all levels of training.
The style is used as the basis for self-defense classes offered
by the University of Akron, Akron, Ohio. The beginners Hakko Denshin Ryu study guide
is the text required by the university.
The style, along with other aikijujutsu styles, are used in law enforcement due to the humane aspects of limiting injury.