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SHIHAN-DAI Jacob Greasley
Sensei Jacob has been practising martial arts for more than 25 years. He trained extensively in Japan for several years in jujutsu and swordsmanship and was awarded the rank of 5th Degree Black Belt, Shihan-dai in jujutsu in Hiroshima, Japan. Additionally, Sensei Jacob was promoted to 5th Degree Black Belt in Shito Ryu karate in Kobe, Japan. He holds the 'Kyoshi' teaching license and is a disciple  of grandmaster Sei Iwasa, 9th Dan.


He turned to martial arts training as a teenager and after several years of service in the British military he founded Jikan Dojo in East London where he teaches many children and adults today.

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Though an engineer by profession, with a masters degree in electrical engineering he is also an experienced SIA security officer. He holds a DBS (formerly CRB) background check, along with qualifications in karate & sports coaching, Safeguarding & Protecting Children and First Aid.


Sensei Jacob regularly travels to Europe and Japan to teach, demonstrate and practice Japanese martial arts. He has also co-hosted seminars in the Caribbean and USA.


With guidance from his own teachers and mentors he works to promote traditional martial arts not only as a means of self-defence but also for personal growth and moral development. You can read many of his articles in our blog here..



SENSEI David Christenson


Sensei David, holds a 2nd Degree Black Belt in Shito Ryu karate and has been training for over 20 yrs. He is originally from Fresno, California USA and settled in the UK over a decade ago. 

Despite his commitments as an entrepeneur in the tech field, David sensei manages to practice regularly and for many years has been a great leader and inspirational figure in Jikan Dojo and the wider Jikan Kai association. He regularly supports and teaches classes and is the main point of contact in the absence of the main instructor.


Over the years David sensei has regularly participated in our local seminars and our training trips abroad, in additional to participation in kobudo (weaponry) and jujutsu training from time to time. He has an enhanced DBS and qualifications in karate coaching and first aid.

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