It is his friend Michel Coquet (Sword Teacher and representative to France for the Tenshin Shoden Katori Shinto Ryu of Headmaster Otaké) who helped him discover Shugendo through different publications. Michel Coquet had lived 5 years in Japan from 1969 through 1974. At the beginning of the year 1980, when Sylvain went to Japan, he started to practise Shingon Buddhism and meditation under a waterfall with the monk Suzumura Shinkai who was the Head of the temple of Oyamadéra-Daisenji in the town of Ishihara-shi, part of the large southern suburbs of Tokyo. It has been a sacred practice area for shugenja for 1300 years.

   Then Sylvain practised meditation under the Ryutaki Waterfall on Mount Takao with Master Yamaguchi Gogen (10th dan of Goju- ryu Karate), who was nicknamed "the Cat". Since that time, both Suzumura-Sensei and Yamaguchi-Sensei have passed away. During the next 10 years, each time that Sylvain went back to Japan, he practiced as a Yamabushi layman (Ubasoku). In 1989 , he read the french translation of a japanese work written by the Antropologist and Shugendo specialist Anne Bouchy on the Yamabushi Jitsukaga who lived during Meiji period. Sylvain found in this work a moment of great revelation!

   In 1990, he settled definitively in Japan to live and became a full monk-yamabushi (sôgi-yamabushi) with the name Kuban Jakkoin. He stayed for 12 years, studying the doctrines and the rites of esoteric Buddhism of the Shingon school of Mount Koya. He also studied the Tozan school of Shugendo under Archbishop Nakada (Dai- Sôjô) at Shinagawa-dera temple in Tokyo. While studying Tozan-ha, Sylvain also studied with Saito Sensei of Nyonindo temple, learning secret Hora gai (Conch shell) methods and other practices.

   At the end of the first year, he established his residence in the mountains of the province of Mikawa to study the work of the Zen Master, Suzuki Shôsan, who died on June 16, 1665. Every year Sylvain would complete the pilgrimage to the Hagouro mountains (in the North-West of Japan). In 1992 he was ordained officially as a monk-yamabushi of the imperial Temple of Shôgôin in Kyoto. The Shôgôin temple was founded by the emperor Gô-Shirakawa who had built this monastery for Archbishop Zôyô, approximately 900 years ago, to thank him for being his guide 33 times during the pilgrimage of the Ominé mountains.

   Sylvain lived in Kyoto for five years to learn the rituals, ceremonies, chants and songs in accordance with the standards of Shôgôin temple. By 1992, he already had completed (on foot wearing traditional sandals of straw), the pilgrimage around the island of Shikoku and its 88 temples, a distance of 1500 kms.

   Sylvain wished to deepen his spiritual knowledge and martial skills (Sylvain has been practising Japanese martial arts for 27 years) through further ascetic practices. In 1995, in the Kannen-kutsu cave, located in cliff of the small island of Tomogashima (opposite the harbour city of Wakayama, in the south of Osaka), he carried out the difficult 21 day long fasting practice (without eating and especially without drinking water), called Mizudachi no Gyo.

   In 1996, after two years of preparation, Sylvain followed in the footsteps of his Master of Shugendo, Reverend Nakai (Head of Kizo Temple in the village of Yoshino), and made the 100 day retreat in the cave of Sho (see article in Géo magazine published in October 2000: "a French monk in Japan".) He is only the 64th ascetic to successfully complete this difficult retreat, following the examples of such shugenja as En-No-gyoja, Nichizo shonin, Gyoson... and Jitsukaga. In 1999, in celebration of 1300th Anniversary of the death of the founder of the shugendo, five friends (three French: Karim, Pascal and Karine , one Swiss : Frederic and one American : Bob Meismer) join Sylvain and the yamabushi of the Shogoin temple, to carry out the pilgrimages in the Haguro & Ominé mountains. After becoming a Yamabushi priest, Sylvain received the charge to care about a small hermitage in Mikawa province: the temple of Nyoraiji. But as often times in Shugendo, the priests must have a secular job to keep life. Sylvain was the manager of the Overseas department in the Advertising Agency Soho-Pvision in Japan.

   But the hardest asceticism still remained to be practiced! He arrived home to France in the summer of 2001. Shortly after arriving Kuban was in an accident and suffered a a blow to the head which resulted in cerebral hemorrhage. He spent the following month in a coma, suffering elevated pressure on the brain that stopped his heart three separate times. He underwent cranial probes to measure the blood pressure surrounding his brain, lived on a respirator and was fed via a stomach tube. During this time Reverend Kuban had very particular experiences of the world of "the hereafter".

   An intensive rehabilitation enabled him to leave the CHU Hospital of Nice after four months. He made prayers addressed to the divinities of Shugendo and by the summer of 2002, he was walking again, in the Shogoin temple in Kyoto, addressing his thanks, one on one with the statue of the ascetic En-No gyoja.

   Sylvain sought the benefits of the hot springs in Yunominé, immersing himself in the mineral rich waters in order to obtain a complete and fast healing. The hamlet of Yunominé is located close to the Nachi Waterfalls, the largest and most famous in Japan, and considered to be one of the birthplaces of Shugendo practice.

   It is said that En-No-Gyoja used 7 of his lives to be able to become "the ascetic". The accident in 2001 brought the total of ‘deaths’ for Sylvain to 6.

-A serious car accident in 1988
- In 1989 during practice on Misen mountain the yamabushi of the Shogoin temple could not feel his pulse when he collapsed from exhaustion.
- During the pilgrimage of Shikoku, on the last day of the practice, a car burst its front tire and from 10 meters away struck him without any physical injury.
- The asceticisms in the caves of Kannen and Sho were lived like "small deaths"

   “It is amusing to remark how life evolves around those pivotal moments that indicate the stage or progress of your life. “ (Sylvain)

   In 2005, he founded the Wolfpack-Team, a free skiing association for the rehabilitation of people who have suffered brain injuries. Skiing is a winter meditation inside the mountains.

   In 2008, he founded the SHOMUDO-han hermitage to practice, in France, the Shugendo traditions & share knowledge acquired in Japan. He created the SHUGENDO-FRANCE association, which is officially affiliated to the French Buddhist Union (union bouddhiste de france).

   At present, Sylvain (Kûban) has the desire to spread in the West the teaching of Shugendo. He has written approximately 50 articles in "Karate-bushido" magazine over a period of 5 years, focused on the practices of Shugendo and the Japanese martial arts. He plans to undertake teaching again in France soon, focusing on the Traditional schools of Japanese martial arts (particularly focused on sword and kempo) along with the practices of Shugendo. Sylvain is also a “mental coach” for french pro-skiers and author of many articles on Shugendo, as well as sometimes consulting for TV programs on Japanese subjects.