What Ibara calls Nagisa is 閣下 (kakka), usually translated as Your Excellency or Your Highness. In Japanese military, they apparently add this honorific to military leaders two star rank and above, and even those referred with this honorific sometimes refer others of the same rank with it.
Villain - 3
Whenever there’s talk of series/affiliate schools, affiliate companies, etc, the ‘affiliate’ part was 系列 (keiretsu) in the original Japanese. It’s apparently a Japanese economic system of affiliated corporations and shareholdings, and its horizontal structure contrasts zaibatsu’s vertical one, but I’m unfortunately not too well-read in economy to explain, or to know if I’m making a mistake by simplifying it as just affiliate.