Complex sentence: Many of the main characters within the series are members of this organization, its members include Sousuke Sagara, Melissa Mao, Kurz Weber and Teletha Tessa Testarossa.
Split into simpler sentences: Many of the main characters within the series are members of this organization. Its members include Sousuke Sagara, Melissa Mao, Kurz Weber and Teletha Tessa Testarossa.