Noboru Ohtaka, the founder of Ohtaka Enzyme and inventor of the Ion House, established the Ohtaka Enzyme Research Institute in Hattori Village in southwestern Hokkaido in 1935 and began developing an enzyme fertilizer using sawdust. In the process, he got the idea of “sawdust enzyme hot bath” after he felt a pleasant sensation when he put his feet in “sawdust compost that fermented and emitted heat,” and saw that people in his neighborhood with neuralgia and rheumatism improved and their skin conditions improved.
In 1955 Noboru moved to Obihiro City and began to work on enzyme farming in earnest, establishing the Ohtaka Enzyme Science Institute and teaching farming in Toyokoro Town. At the time, he was exploring the feasibility of enzyme farming for rice cultivation in cold regions, and it is said that he actually raised the water temperature by more than 3°C. A trial-and-error process began to see if the fermentation heat of sawdust compost could be used for hot bath facilities.
Later, around 1962, the “Ohtaka Health Club ” was established in Sapporo, and Noboru became the center of a facility that used enzyme fasting and other enzyme baths to treat illnesses. This was followed by the establishment of enzyme baths for therapeutic purposes in Ayabe City, Kyoto Prefecture in 1963, in Tsurumi-ku, Yokohama City in 1964, and in Tokuda Hospital, and in Asahikawa City, Hokkaido in 1966.
At that time, enzyme therapy consisted of drinking only 600 ml a day of water made of Ohtaka enzyme solution and St. John’s Wort extract with a little salt added, taking an enzyme bath twice a day, morning and evening, and receiving abdominal pressure massage.
According to records, 13 Ion Houses were opened nationwide in 1971.
For the 1972 Sapporo Olympics, a fermented sawdust bath “ion house” was constructed in Makomanai Town, Hokkaido, at a cost of approximately 50 million yen with the cooperation of Ichiro Hatta, then a member of the House of Councilors. In terms of today’s monetary value, this is equivalent to approximately 200 million yen.
The rights to the miso and soy sauce plant in Otaru were transferred to Donan Foods, which produced the first special enzyme “Fusetsu” at its brewing facility in 1975. That facility was then used as a rehabilitation facility for Noboru who fell ill around 1979-5, and the current advancement, Otaru Ion House, was built and opened as a commercial facility in 2005.
Initially, the basic method of sawdust fermentation was to boil and dissolve potatoes or soybeans, add five starch-based enzymes (sake) and one plant-based fermentation stock solution, and increase the number of heat-generating Bacillus subtilis to double the number of original species. However, the controlled use of pure cultures of fever-generating bacteria made it possible to maintain stable fever.