Complex sentence: On April, 2011, Sumitomo Corporation acquired CSK Corporation by Takeover, then on October, 2011, Sumitomo Computer System Corporation and CSK Corporation were merged, the company name was changed to SCSK Corporation.
Split into simpler sentences: On April, 2011, Sumitomo Corporation acquired CSK Corporation through a Takeover. On 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 to SCSK Corporation.