Chroma are bounty hunters for hire that deal with all manner of requests, including monster subjugation. A thirteen-year-old girl named Marona lives on Phantom Isle after losing both of her parents at a young age. Her parents had lost their lives during their jobs as Chroma and now she must become a Chroma to earn money. However, work as a Chroma is difficult and many hold her in disdain as the 'Cursed Girl' because of her ability to talk to and manipulate phantoms.

Thankfully, she's not alone since she has the help of the phantom named Ash, a friend of her parents that had died alongside them in a mission. Marona's parents' dying wish for Ash was to have him protect their daughter. Now Ash does everything he can to help defend Marona from the hardships of the world.