Firefly, whose real name is Sam, is a prominent character in Honkai: Star Rail, especially tied to the Penacony storyline. She appears as a mysterious, gentle girl connected to the Stellaron Hunters and is known for her emotional depth, hidden identity, and tragic circumstances. Her role in the series centers on uncovering the truth behind her condition and her relationship with the Trailblazer, while also serving as a key figure in the conflict surrounding Penacony.