From1941From Post-war Recovery to Kurobe Dam
After surviving the difficult wartime period, immediately after the war Kumagai Gumi established a Construction Division. This allowed the company to make a major contribution to Japan's recovery in the construction field as well as the civil engineering field that was its forte. The Kurobegawa No.4 Power Station construction project that was planned to eliminate serious electricity shortage during the high economic growth period, and Kumagai Gumi began construction of the Omachi Tunnel (currently Kanden Tunnel) which required difficult construction would remain in the annuals of Japan's civil engineering history. This struggle was even immortalized in the novel and movie Kurobe no Taiyo (Sun of Kurobe).
1945
- April
- Tokyo Office completely incinerated by an aerial bombardment
- May
- A temporary structure was erected on the site of the burned Tokyo Kumagai secondary residence to use as an office and dormitory.
- July
- Kumagai Gumi Head Office burned in the aerial bombardment of Fukui City
1946
- May
- Nagoya Plant operations begun (later Toyokawa Plant, currently Technos Co., Ltd. )
1947
- June
- Technology Research Office established (within the Tokyo Office)
1948
- May
- Registered in the Japan Armature Baseball Association (Baseball Team established)
1952
- April
- Registered in the Basketball Industrial & Commercial League (Basketball Team established)
1954
- September
- Construction of the new Tokyo Office building completed
1955
- April
- Construction completed of the Higashi-Ueda Power Station tunnel which set a monthly progress record of 218.2m and used the full-face excavation method for the first time in Japan.
1956
- August
- Construction completed of the Kanmon National Road Shimonoseki Entrance Tunnel using the roof shield method for the first time in Japan
1957
- August
- Won the 28th Intercity Baseball Tournament.(Also won the 31st and 37th Intercity Baseball Tournaments)
- September
- Winning at the 3rd World Baseball Championship (in Detroit）
1958
- February
- Kuroyon/Omachi Tunnel opens
