Sonic! Software Planning
From Game Developer Research Institute
Sonic! Software Planning (株式会社ソニック; Sonic Co., Ltd.) was a subsidiary of Sega headed by Hiroyuki Takahashi (高橋宏之), former president of Climax Entertainment. It was established on June 12, 1991. Sega owned 85% of the company originally, while Climax owned 6.25%, and Takahashi owned 4%. 
On April 4, 1994 , Takahashi established Camelot Software Planning after being asked to develop software for the PlayStation.