Complex sentence: Despite having amazing powers and a troubled and strict past, Koyuki is very carefree, optimistic, and eccentric, but believes in what is right and protects her friends with all her might.
Split into simpler sentences: Despite having amazing powers and a strict past, Koyuki is mostly carefree, optimistic, but in various occasions, eccentric. She believes in what is right and protects her friends with all her might.