Noa Yūki is a second-year student at Kuho Girls Academy and a major character in the story. She is the founder and leader of the Valhalla Society, an organization she created to act as a force for justice and maintain order within the community. Noa possesses a strong and uncompromising sense of right and wrong; she loves righteousness and despises evil with a passion that resembles that of a classic hero. On the surface, she can come across as unfriendly and quick to be suspicious of strangers, but this reserved exterior hides a pronounced chuunibyou side—a flair for dramatic, self-styled heroism that she fully embraces in her actions and dialogue. She is also notably fond of parfaits, a simple pleasure that contrasts with her serious demeanor. Her artifact is known as the Order, which grants her the ability to judge those she perceives as sinners and to inflict a punishment of her choosing. This power makes her a key asset in the conflict surrounding the mysterious petrification incidents in the town. Initially operating somewhat independently, Noa eventually includes Kakeru Niimi and others as members of the Valhalla Society without their explicit consent, and she works alongside them to solve the unfolding mystery. Throughout the story, her initial bluntness and suspicion give way to a more cooperative and honest partnership, and she is able to acknowledge her own mistakes without making excuses. Her powerful conviction and willingness to repeatedly act as a judge make her a determined force in the fight against the mastermind behind the artifacts and the chaos they cause.