Complex sentence: Sato left the Takada Dojo with Sakuraba in April 2006, and was one of the initial members of the gym Laughter7 that was founded by Sakuraba in September 2007.
Split into simpler sentences: Sato left the Takada Dojo with Sakuraba in April 2006. And, he is one of the initial members of the gym Laughter7 sponsored by Sakuraba in September 2007.