Complex sentence: Akari, a research doctor at Circus said that Nai has the cellular structure of a human and a "niji", a small delicate creature found in the forest he came from, and that these cells have managed to coexist unlike the Varuga.
Split into simpler sentences: Akari, a research doctor at Circus said that Nai has the cellular structure of a human and a "niji", a small delicate creature found in the forest he came from. And that these cells have managed to coexist unlike the Varuga.