The Four Great Houses (
四大名門) are Erebonia's four greatest noble families. Each House upholds the highest of noble traditions and influence over the Imperial provinces entrusted to them by the emperor.
- Duke Cayenne: Former lord and leader of the Four Great Noble Houses, he was also the ruler of the Lamarre Province before his arrest. He was revealed to be a descendant of the Arnor Family following the removed Royal family member, Orthros Reise Arnor. Like his ancestor, he was removed from power after the Erebonian Civil War's end.
- 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.
- 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.
- Marquis 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.