Blood Ocean by Weston Ochse
Kavika Kamalani is a Pali Boy, a post-plague heir to an ancient Hawai'ian warrior tradition that believes in overcoming death by embracing one's fears and living large. His life on the Nomi No Toshi, the floating city, is turned upside down when one of his friends dies, harvested for his blood, and he sets out to find the killer. Kidnapped himself and subjected to a terrifying transformation, Kavika must embrace the ultimate fear - death itself - if he, his loved ones, and the Pali Boys themselves are to survive.