사대명문

The Four Great Houses (四大名門(よんだいめいもん)) are Erebonia's four most powerful noble families. Each House upholds the highest of noble traditions and influence over the Imperial provinces entrusted to them by the emperor.

Organisation

Bold indicates most recent official leader.

House Cayenne

• Alfred de Cayenne: The previous Duke Cayenne who died in maritime accident; his position was taken over by his younger brother Croire de Cayenne.
• Croire de Cayenne: Former lord and leader of the Four Great Noble Houses who holds the title of Duke, he was also the ruler of the Lamare Province before his arrest. He was revealed to be a descendant of the Arnor Family from the line of the removed Royal family member, Orthros Reise Arnor. Like his ancestor, he was removed from power after the Erebonian Civil War's end.
  
• Mildine Juzelith de Cayenne: Daughter of the late Duke Alfred de Cayenne, she was confined to St. Astraia Girls' School by her uncle Croire after her parents' death. With Croire's arrest and the backing of the other Great Houses, she was appointed as the heir apparent to House Cayenne. She leaves most official matters in the hands of her granduncle, Wilhelm Ballad, until she finishes her education at Thors Branch Campus and official assume her role as Duchess after she gratulated.

House Albarea

• Helmut Albarea: Lord of the Kreuzen Province who holds the title of Duke. He was arrested by his second son for ordering the pillaging of Celdic.
• Rufus Albarea: The first-born son of the duke and a member of Thors Military Academy's board of directors. He is the primary leader of the Ironbloods, and was tasked to take out the Noble Alliance from within.
• Jusis Albarea: The duke's illegitimate second son and a student of Thors Military Academy's experimental Class VII. Following the Erebonian Civil War, he took up the role of Kreuzen's new lord after his father's arrest.
  

House Rogner

• Gerhart Rogner: Lord of the Nortia Province who holds the title of Marquis.
• Heidel Rogner: The marquis's younger brother who temporarily held the position of the Reinford Group's director following the Noble Alliance's hostile takeover. Following the infiltration of the Reinford Group building by Class VII, he was removed from the position and arrested.
• Angelica Rogner: The marquis's rebellious daughter and a student of Thors Military Academy's Class I.
  

House Hyarms

• Fernand Hyarms: Lord of the Sutherland Province who holds the title of Marquis.
• Patrick T. Hyarms: The third-born son of Marquis Hyarms and a student of Thors Military Academy's Class I.
  

Gallery

• 
  The four great house's domains of Erebonia.
• 
  The capital cities of each Great House; Bareahard, Ordis, Saint-Arkh and Roer.