An abrupt departure from the normal life he once lead, Saito must deal with being Louise's familiar. Unhappy with the arrogance of nobles, Saito exposes Guiche's two-timing nature as an act of revenge. This of course, provokes Guiche into challenging him to a a duel. Despite being severely beaten up by Guiche's magic, Saito refuses to bow down. Impressed, Guiche tosses him a sword to even up the playing field. In a completely unexpected turn of events, the runes etched on Saito's hands begin to glow the moment he grasps the sword. Feeling a surge of energy, Saito manages to defeat Guiche. However, he soon collapses after the fight from fatigue.

It's summer vacation and many students are traveling back to their families. Kirche goes along with Tabitha to her home on invitation, leaving Louise and Saito alone for once. However, mischief is still plentiful. Upset at Guiche's continued flirting with other girls, Montmorency creates a love potion and plots to have Guiche take it. Meanwhile, Saito obtains a large pot that was about to be thrown away and converts it into a makeshift hot tub, similar to the hot springs in Japan. While bathing in it at night, Siesta happens to pass by and much to Saito's embarrassment joins him. Seeing this, Louise becomes so frustrated that she interrupts Montmorency's plans by gulping the drink laced with the before mentioned love potion. As can be expected, when Saito returns to her room, Louise falls completely in love, causing many more problems.