Augusta Vradica is the Empress of the New Human Empire, known by her real name Seth Nightroad. She is the youngest among the Nightroad siblings and recognized as the third Crusnik. Serving in the Alliance Aerospace Navy, Seth regarded Lilith as a maternal figure and felt deep sisterly affection for Abel. When Cain suffered fatal injuries in an accident, Seth injected him with 100% Crusnik serum, saving his life but altering his personality for the worse. Following Cain's murder of Lilith during the war, Seth teamed up with Abel to confront him, ultimately managing to eject him into space through an airlock.
Among the four Crusnik siblings, Seth has spent the most time with Methuselah, yet similar to Abel, she abstains from feeding on them. Around eight centuries ago, Augusta Vradica guided the Methuselah to lands where the Empire would eventually be established, rescuing them from persecution. She contributed to restoring nature to these regions, bringing them back to their pre-Armageddon splendor. Subsequently, she became the Empress of the New Human Empire, ruling her kingdom as its core. As Empress, Seth is perceived as a mother by her people, treating her subjects like her own children. However, throughout the centuries, many of her courtiers and servants have never seen her face due to the heavy veils she wears to conceal her appearance and the voice modifier she uses. Despite aging, she retains the appearance of a young girl while being over nine hundred years old. It is suggested that she avoids declaring war on Vatican territories out of respect for her brother’s support for humans. Familiar with Abel, Seth has noted he is inexplicably popular among women.
During a conspiracy to dethrone her, Seth disguised herself as a tea-seller and medical student in Byzantium's human district. There, she encountered Ion Fortuna and Sister Esther Blanchett without revealing her identity. Later, she alerted Abel and Asthe when Ion and Esther were endangered, even rescuing Esther from one of Dietrich's puppets.
Upon activating her Crusnik powers, Seth's eyes turn red, her lips greenish-blue, her voice deepens, fairy-like wings emerge from her back, and giant tuning forks made of blood appear in her hands. In this state, she can almost instantaneously disintegrate her enemies. Similar to Cain, her abilities seem to revolve around sound wave manipulation, which she refers to as "The Fire of Sound."
