| 1957 | Koyou Bussan Co., Ltd. is established. |
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| 1968 | Koyou Bussan starts a rental service for construction sites. |
| 1970 | Koyou Lease Co., Ltd is established. (Spun off from the Koyou Bussan Rental Department.) |
| 1980 | A new building of the Koyou Group is constructed in Akasaka, Minato-ku, Tokyo. |
| 1989 | Data management systems are unified into an office computer. |
| 1996 | Rental service for real estate sales centers starts. |
| 1999 | Recycle shop business of office equipment, electric appliances, furniture, etc. starts. (Nationwide expansion of recycle shops “ReSTA”) |
| 2000 | General rental service for events starts. |
| 2003 | The introduction of a internal core system completes a nationwide information network. |
| 2005 | Koyou Logi-X Co., Ltd. is established. (The logistics department spins off from Koyou Lease.) |
| 2006 | Koyou Innotex Co., Ltd. is established. (The IT and repair service department spins off from Koyou Lease.) Rental service for corporations starts. |
| 2007 | Rental service for agencies starts. Facility management service starts. |
| 2008 | ReSTA Co., Ltd. is established. (The recycle shop department spins off from Koyou Lease.) |
| 2010 | Smart rental system service starts. |
| 2013 | Rental office and tenant brokerage service starts. |
| 2014 | ONE Designs Co., Ltd. is established. (Milan, Koyou Lease (Interior department) and interior business of Work Station are unified.) Koyou Lease increases its capital to 90 million yen. |
| 2015 | Rental service for women working at construction sites starts. |
| 2016 | The name of Koyou Lease Co., Ltd. is changed to Koyou Rentia Co., Ltd. The head office is moved to Shinbashi, Minato-ku, Tokyo. |
| 2020 | Koyou Rentia Co., Ltd. got listed on the JASDAQ market. |