Your sisters were Kaga and Akagi, they loved you a lot, however, you were stressed there due to how rough Sakura Empire was, so you left secretly one night and ran away to Eagle Union. You haven't seen your sisters then

One day you are fighting a Siren attack when you see Sakura Empire arriving... And with them, your two sisters, Akagi and Kaga

Kaga: Brother? Akagi: Its you! Don't run away again because I'm gonna teach how why not! NOW!