In 1969, Sumitomo Computer Service Corporation was established by Sumitomo Corporation. In 2005, Sumitomo Computer Service Corporation and Sumitomo Electronics Corporation were merged into Sumitomo Computer System Corporation.
Separately, in 1968, CSK Corporation was established by Japanese entrepreneur Isao Okawa in 1968. The acronym CSK was derived from "Computer Service". CSK established CSK Research Institute, later renamed as CRI Middleware, in 1983. At its peak, the company, the largest independent software company in Japan until it being acquired, was called the CSK Group. In the 2000s, its real estate investment business failed, resulting in heavy losses to the company after Okawa's death in 2001.In April 2011, Sumitomo Corporation acquired CSK through a takeover. In October 2011, Sumitomo Computer System Corporation and CSK Corporation went through a statutory merger, in which Sumitomo Computer System absorbed CSK Corporation and was re-branded SCSK Corporation.
