SINANEN HOLDINGS Group became a holding company on October 1, 2015. See the website of SINANEN HOLDINGS for the history of the Group as a whole.
| October 2015 | Changed company name to SINANEN Co., Ltd. as SINANEN Group became a holding company |
| January 2016 | Acquired all shares of Nippon Solar Electric Power Co., Ltd. |
| July 2016 | Completed construction of Ten-ei Village Solar Park |
| December 2016 | Withdrew from solid fuel business |
| June 2017 | Took over a part of the business of SINANEN FACILITIES Co., Ltd. |
| April 2018 | Established PV Service Department to carry out solar power-related business |
| June 2018 | Took over a part of the business of Solar Power Support Center Co., Ltd. |
| January 2019 | Moved the head office to 3-5-27 Mita, Minato-ku, Tokyo |
| March 2019 | Founded SINANEN KOREA Co., Ltd. |
| February 2020 | Founded Sinagy Revo Co., Ltd. |
| December 2020 | Founded SYNERGY TRANSPORT Co., Ltd. |
| April 2023 | Acquired Sinagy Revo Co., Ltd. |
| July 2024 | Moved the head office to 1-39-20 Higashishinagawa, Shinagawa-ku, Tokyo |