Kazuo KOGA, the founder, head of Koga Hospital, established an internal medicine clinic, called Koga Clinic.

The clinic was re-established as Koga Hospital.

The hospital started to provide dialysis treatment.

MEDICAL CORPORATION TENJINKAI was founded

The Wakakusa At-home nursing Station was established.

Shin Koga Hospital was founded, along with the neurosurgery and orthopedic surgery departments.

The Gamma Knife Center was opened in Shin Koga Hospital.

Shin Koga Hospital was accredited with Ver.2.0 Hospital Faculty Valuation by the Japan Council for Quality Health Care.

The Koga Hospital Day Care Center was opened.

The Tenjin Care Plan service was started.

Koga Hospital 21 was founded. Koga Hospital was renamed to Koga Clinic.

PET-CT Imaging Center was established in Koga Hospital 21.

Shin Koga Hospital was accredited with Ver.4.0. Hospital Faculty Valuation by the Japan Council for Quality Health Care.

Koga Hospital 21 was accredited with Ver.4.0 Hospital Faculty Valuation by the Japan Council for Quality Health Care.

Koga Clinic received the Japan Ningen Dock Hospital Faculty Valuation by the Japan Society of Ningen Dock.

Koga Clinic was renamed to Shin Koga Clinic.

Diabetes Center was opened on the third floor of Shin Koga Hospital.

The governor of Fukuoka approves the Tenjinkai as a social medical corporation.

Koga Hospital 21 opens the Palliative Care Ward.

The Hebaru clinic is established.

Koga Care Avenue was established in Miyanojin.

Shin Koga Hospital was accredited with the 3rdG:Ver.1.0 Hospital Faculty Valuation by the Japan Council for Quality Health care.

Koga 21 Care Home was established.
Koga Hospital 21 was accredited with the 3rdG:Ver.1.0 Hospital Faculty Valuation by the Japan Society of Ningen Dock.

Shin Koga Clinic received the renewed Japan Ningen Dock Hospital Faculty Valuation by the Japan Society of Ningen Dock.

Koga Care Avenue Nobusuma was established.

Shin Koga Hospital expanded, adding the eastern wing.
Shin Koga Hospital was designated by the governor of Fukuoka prefecture as a medical institute for type-2 infectious diseases.

The Koga International Nursing School was opened.

Shin Koga Hospital and Koga Hospital 21 were certified and recommended as "Japan International Hospitals" by Medical excellence Japan (MEJ)