History
| 1963 | Wakayama Nainenki Kosakusho was founded in Tosa-cho, WakayamaCity to engage in the business of overhauling internal combustion engines. |
| 1968 | Wakayama Nainenki Co., Ltd. was incorporated with a capital of JPY1.5 million. An additional factory was built in haneta, Minabe-cho, for manufacturing motorcycle brake shoes. |
| 1969 | Started manufacturing die-cast clutch shoes, and supplying them as clutch assemblies for small sized engines. |
| 1973 | The capital was increased to JPY 6 million.An additional factory was built in Nishifuki, Koya-cho, for manufacturing brake shoes. |
| 1974 | The capital was increased to JPY 9 million. |
| 1976 | The Main Factory was expanded, adding the Die-casting Section. The new Minabe Factory was built, integrating the Fuki factory and the old Minabe factory. |
| 1978 | The capital was increased to JPY 10 million. |
| 1979 | The Main Factory was expanded, and the Designing and Research Section was established and enhanced. |
| 1981 | The Main Factory was expanded, enlarging the work space.The capital was increased to JPY 20 million.The Numazu Factory was built to operate as a die-casting factory. |
| 1982 | Started manufacturing rearview mirror components for automobiles. |
| 1984 | Started manufacturing compressor pistons for air conditioners.Transferred the overhaul business of internal combustion engines and automotive brakes to another company, and started operating completely as a manufacturing factory. |
| 1985 | Started the integrated manufacturing of small sized engine pistons from casting to processing in Nakanoshima, WakayamaCity. (The Nakanoshima Factory was built.) |
| 1986 | An additional factory for piston processing was built on the west side of the Main Factory premises. |
| 1988 | Shokibai Co., Ltd. was incorporated. |
| 1989 | The Head Office building was completed. |
| 1990 | The lineup of centrifugal clutches was enhanced. |
| 1991 | Acquired Yamamoto Mfg. Co., Ltd.The die-casting factories were integrated into the Main Factory. |
| 1992 | Won the Best Award (Labor Minister Award) at the Workplace Improvement Contest held by the Association of Employment Development for Senior Citizens of Labor Ministry (the current Ministry of Health, Labour and Welfare). |
| 1994 | A third sector company Winnac Co., Ltd. was jointly incorporated by WakayamaPrefecture, WakayamaCity and AcroNainen as a company to employ a large number of severely disabled people. |
| 1995 | The capital was increased to JPY 25 million, and then doubled to JPY 50 million. |
| 1996 | Received the “Superior Forward-Looking Businesses Award” from Nikkei Inc. |
| 1997 | The main store of Shokibai Co., Ltd. was built and opened in Nishitakamatsu, Wakayama City. |
| 1999 | Acquired ISO 9001 certification. |
| 2001 | The capital was increased to JPY 110 million.Shanghai Censi Automobile Parts Co., Ltd. was incorporated in Shanghai, China. |
| 2003 | The capital was increased to JPY 147.5 million.The company name was changed from Wakayama Nainenki Co., Ltd. to Acro Nainen Co., Ltd. |
| 2004 | Minabe Factory was relocated to TanabeCity, and renamed as Tanabe Factory.The clutch section was transferred from Main Factory to Tanabe Factory. |
| 2006 | Chosen as one of the “300 Energetic Small and Medium Manufacturing Enterprises” (by Small and Medium Enterprise Agency, Ministry of Economy, Trade and Industry). |
| 2007 | ACRO (THAILAND) CO., LTD. was incorporated. |
| 2010 | The factory building for ACRO (THAILAND) CO., LTD. was completed. |
| 2013 | Huzhou Shengxi Electronics & Technology Co., Ltd. was incorporated in Huzhou, China. |
| 2015 | Kiichi Katsumoto assumes office as Chairman,Masato Katsumoto as President. |
| 2018 | Fully automatic die casting piston manufacturing line completed at Tanabe factory |
| 2018 | Established Sole Proprietorship (Maanshan) Co., Ltd. in Maanshan City, Anhui Province, China. |
| 2021 | Nagano factory closed |
| 2021 | Merged with Winnac Co., Ltd., a wholly owned subsidiary. Transferred the recycled toner business to Winworks, a general incorporated association. |
