| 1953/12 | Niigata's first industrial processer and wholesaler of polyethylene, Kumagai was founded in Niigata City by current Chairman Daisuke Kumagai |
|---|---|
| 1955/11 | Polyethylene tube manufacturing equipment installed |
| 1960/01 | Sales department reorganized as Daiwa Plastic Co., Ltd. with each processing department reorganized under Kumagai Shoten Co., Ltd. Capital 1.5 million yen |
| 1963/07 | New plant built in Shimokido, Niigata-shi |
| 1964/09 | Nagano Sales Office opened |
| 1964/12 | Sendai Sales Office opened |
| 1968/11 | Capital 10 million yen |
| 1969/01 | Hachinohe Sales Office opened. |
| 1970/06 | Company name change to KUMAGAI CO., LTD.. |
| 1972/09 | New Head Office built |
| 1973/07 | Aomori Kumagai Co., Ltd. established and merged with Hachinohe Branch Office |
| 1974/07 | Tokyo Sales Office opened Capital 22.5 million yen |
| 1974/10 | Manufacturing department separated off to become KZM Co., Ltd.Manufacturing department separated off to become KZM Co., Ltd.Manufacturing department separated off to become KZM Co., Ltd. |
| 1980/05 | Yamagata Sales Office opened |
| 1982/02 | Construction of Iwamuro Factory completed |
| 1983/07 | Construction of Kyogase Factory completed |
| 1983/11 | Iwamuro Factory received “certified factory” designation from the Flexible Packaging Hygiene Association |
| 1993/05 | Capital 30 million yen |
| 1994/06 | Capital 40 million yen |
| 1997/06 | Capital 45 million yen |
| 1998/05 | Capital 49 million yen |
| 1999/03 | Nagoya Sales Office opened |
| 1999/06 | Capital 60 million yen |
| 2000/02 | ISO 14001 certification acquired Head Office, Iwamuro Factory, Kyogase Factory, KZM Co., Ltd. |
| 2005/02 | ISO 9001 certification acquired Entire KUMAGAI CO., LTD., plus KZM Co., Ltd. and Aomori Kumagai Co., Ltd. |
| 2010/04 | Merged with Aomori Kumagai Co., Ltd. to become Aomori Sales Office |
| 2013/02 | West Japan Sales Office established |