"Guilty Crown: Lost Christmas" is a 15-minute OVA set in the same universe as the main "Guilty Crown" series, serving as a prequel that explores the origins of the Apocalypse Virus and the events leading to the collapse of Japan. The story is set in 2029, ten years before the main series, during a time when the Apocalypse Virus, a deadly pandemic, begins to spread. The narrative centers on a young man named Scrooge, a skilled hacker, and his companion Carol, a mysterious girl with a tragic past. Together, they navigate a dystopian Tokyo under martial law, where the government and a shadowy organization known as GHQ are attempting to contain the virus.

Scrooge is tasked with infiltrating a GHQ facility to retrieve a critical piece of data that could potentially halt the spread of the virus. However, the mission takes a dark turn when Carol's true nature is revealed. She is a genetically engineered being, created as a vessel for the Apocalypse Virus, and her existence is tied to the outbreak. As Scrooge uncovers the truth, he is forced to confront the moral implications of his actions and the devastating consequences of GHQ's experiments. The story delves into themes of sacrifice, loss, and the ethical dilemmas surrounding scientific experimentation.

The OVA provides a concise yet impactful exploration of the events that set the stage for the main series, offering insight into the origins of the Apocalypse Virus and the societal collapse that follows. Scrooge's character is defined by his technical prowess and his growing emotional conflict as he grapples with the weight of his decisions. Carol, on the other hand, embodies innocence and tragedy, her fate intertwined with the virus and the broader narrative of the "Guilty Crown" universe. The OVA's pacing is brisk, focusing on key moments that highlight the tension between humanity's survival and the cost of scientific advancement. Through its compact storytelling, "Guilty Crown: Lost Christmas" effectively establishes the foundation for the larger narrative while standing as a self-contained exploration of its themes.