Complex sentence: The story was that a mysterious woman fights with a baldheaded leader of a vicious secret organization, and Shina was playing the woman and Masato Minagawa, the keyboard player of her band, was playing the enemy's leader.
Split into simpler sentences: The story was that a mysterious woman fights with a baldheaded leader of an evil secret society. Sheena played the woman and Masato Minagawa, a keyboard player of her band, played the enemy's leader.