"Louise the Void" is the thirteenth episode of the first season of The Familiar of Zero.
Saito lets Louise know that he will be departing in three days, at the upcoming solar eclipse, in order to return home to Japan, but when she hears this she brushes it off as if she doesn't care, which, angers Saito. He waits for Louise to return from her meeting where the war between Albion and Tristain is declared inevitable. Princess Henrietta begins to organize a military force and thus the headmaster dismisses the school for the time being. Guiche is forced to join the army due to his family being in it as well. Louise walks into a sleeping Saito whereupon she says Good-bye. The next morning, Saito wakes to find a letter in which Louise has written, "You're fired! Just go wherever you want!" Louise decides to join the princess in war. The next day, Saito gets on his fighter plane while Princess Henrietta advances with the Tristain military to intercept the invading Albion force. Saito aids in battle by shooting down Albion's dragon squadrons, who were unable to keep up with the plane's speed. After running out of ammunition for the aircraft's guns, and defeating the dragon squadrons, Saito is attacked by Wardes on a wind dragon, leaving Saito defenseless. Louise unlocks her magic for the first time and casts a powerful spell known as 'Explosion' which destroys the entirety of Albion's aerial attack force. After the battle, with the solar eclipse past and the Zero Fighter nearly destroyed, Saito and Lousie sit by the plane's wreckage where they have an argument once again. They end up kissing, thus renewing the contract between them. They are all awarded medals by the princess, and Tabitha gets the water ring back from the man who stole it from her.