| 1955-03 |
Founded in Matsue City, Shimane Prefecture, as the predecessor of Eight Consultant Co., Ltd., called Yakumo Surveying Company |
| 1955-03 |
Founded in Matsue City, Shimane Prefecture, in March 1955, as the predecessor of Eight Consultant Co., Ltd., called Yakumo Surveying Company |
| 1959-04 |
Founded as Japan Technology Development Co., Ltd. |
| 1959-04 |
Founded in April 1959 as Japan Technology Development Co., Ltd. |
| 2005-10 |
Capital and business alliance between Eight Consultant Co., Ltd. and Japan Technology Development Co., Ltd. |
| 2007-06 |
Established a joint holding company, E.J Holdings Inc., through share transfer between Eight Consultant Co., Ltd. and Japan Technology Development Co., Ltd. (listed on the Second Section of the Tokyo Stock Exchange) |
| 2007-06-01 |
Established on June 1, 2007. |
| 2008-01 |
Subsidiary of Eight Consultant Co., Ltd., Shinkyo Technical Consultant Co., Ltd., renamed to Japan Infrastructure Management Co., Ltd. |
| 2008-01 |
In January 2008, the subsidiary of Eight Consultant Co., Ltd., 'Shinkyo Technical Consultants Co., Ltd.', was renamed to 'Japan Infrastructure Management Co., Ltd.' |
| 2008-01 |
The subsidiary of Eight Consultant Co., Ltd., 'Shinkyo Technical Consultants Co., Ltd.', was renamed to 'Japan Infrastructure Management Co., Ltd.' |
| 2009-06 |
Split Japan Technology Development Co., Ltd., with Eight Consultant Co., Ltd. as the successor, and renamed to Eight Japan Technology Development Co., Ltd. |
| 2009-06 |
In June 2009, Japan Technology Development Co., Ltd. was split, Eight Consultant Co., Ltd. was succeeded, and it was renamed to 'Eight Japan Technology Development Co., Ltd.' |
| 2009-06 |
Japan Technology Development Co., Ltd. was split, Eight Consultant Co., Ltd. was succeeded, and it was renamed to 'Eight Japan Technology Development Co., Ltd.' |
| 2009-06 |
Japan Technology Development Co., Ltd. was renamed to 'EJ Business Partners Co., Ltd.' |
| 2010-06 |
Fully acquired Kinda Sekkei Co., Ltd. |
| 2010-06 |
In June 2010, Kindaisekkei Co., Ltd. became a wholly owned subsidiary. |
| 2010-06 |
Kindaisekkei Co., Ltd. was made a wholly owned subsidiary. |
| 2015-05 |
E.J Business Partners Co., Ltd. was absorbed and merged by Eight Japan Technology Development Co., Ltd. |
| 2015-05 |
In May 2015, 'EJ Business Partners Co., Ltd.' was absorbed and merged by 'Eight Japan Technology Development Co., Ltd.' |
| 2015-05 |
EJ Business Partners Co., Ltd. was absorbed and merged by 'Eight Japan Technology Development Co., Ltd.' |
| 2018-07 |
Designated as a first-section stock on the Tokyo Stock Exchange from the second-section market |
| 2018-07 |
In July 2018, it was designated as a stock of the First Section of the Tokyo Stock Exchange from the Second Section. |
| 2019-03 |
Acquired Arc Consultant Co., Ltd. as a wholly owned subsidiary |
| 2019-03 |
In March 2019, Arc Consultants Co., Ltd. was made a wholly owned subsidiary. |
| 2019-03 |
Fully acquired Ark Consultant Co., Ltd. |
| 2019-07 |
In July 2019, I-Develop Consultants Co., Ltd. was made a wholly owned subsidiary. |
| 2019-07 |
Fully acquired I-Develop Consultants Co., Ltd. |
| 2019-07 |
Fully acquired I-Develop Consultants Co., Ltd. |
| 2019-11 |
In November 2019, Nishikami Architectural Office Co., Ltd. was made a wholly owned subsidiary. |
| 2019-11 |
Fully acquired Nishigami Architectural Office Co., Ltd. |
| 2019-11 |
Fully acquired Nishigami Architectural Office Co., Ltd. |
| 2020-08 |
E.J Japan Technology Development Co., Ltd. (current consolidated subsidiary) established a local subsidiary in Thailand, EJEC (Thailand) Co., Ltd. |
| 2020-08 |
In August 2020, Eight Japan Technology Development (current consolidated subsidiary) established a local subsidiary in Thailand, EJEC (Thailand) Co., Ltd. |
| 2020-09 |
Transferred shares of Urban Development Design Co., Ltd. (current consolidated subsidiary) held by E.J Japan Technology Development Co., Ltd. (current consolidated subsidiary) to the company as a dividend in kind |
| 2020-09 |
In September 2020, the shares of Urban Development Design Co., Ltd., held by Eight Japan Technology Development (current consolidated subsidiary), were inherited by the company through in-kind dividends. |
| 2022-04 |
Moved from the First Section to the Prime Market of the Tokyo Stock Exchange |
| 2022-04 |
In April 2022, it transitioned from the First Section of the Tokyo Stock Exchange to the Prime Market. |
| 2024-05 |
Fully acquired Nissei Planning Co., Ltd. |
| 2024-05 |
In May 2024, Nissho Planning Co., Ltd. was made a wholly owned subsidiary. |
| 2024-09 |
Made Dynamic Engineering Consultants Co., Ltd. an equity-method affiliate; acquired Tokyo Soil Research Co., Ltd. (current consolidated subsidiary) |
| 2024-09 |
In September 2024, Dynamic Engineering Consultants Co., Ltd. became an equity-method affiliate, and Tokyo Soil Research Co., Ltd. (current consolidated subsidiary) was acquired as a subsidiary. |
| 2024-09 |
Made Dynamic Engineering Consultants Co., Ltd. an equity-method affiliate: Acquired Tokyo Soil Research Co., Ltd. (currently a consolidated subsidiary) |
| 2025 |
Held the 7th Research Presentation Meeting of Yakumo Environmental Science Promotion Foundation, a public interest incorporated foundation |
| 2026-07 |
Acquired Meteorological Engineering Laboratory Co., Ltd. (currently a consolidated subsidiary) |
