Firefly is an orphan who has been living in the shadows to continue living. Born with a life-threatening disease, the only person who is capable of keeping her disease at bay is an alchemist who lives in the royal castle, and charges high prices for each dose of her medicine, causing Firefly to resort to drastic measures to stay alive. She is a natural beauty, making it possible she might have been of noble descent. She yearns for a normal, peaceful life as an ordinary girl living as a noble.