Complex sentence: Suu usually wears a raincoat and boots (given to her by Kimihito) out of necessity--any other clothes will get soaked in slime, and all small objects will pass through her membrane skin and stay suspended in her body fluid.
Split into simpler sentences: Suu usually wears a raincoat and boots (given to her by Kimihito) out of necessity. This is because any other clothes will get soaked in slime, and all small objects will pass through her membrane skin and stay suspended in her body fluid.