Zero's Familiar Chevailier(2010)

Zero no Tsukaima Chevalier

War rages on between Tristain and Albion, and the inept mage Louise has a new top-secret mission. But before she can take on the enemies of her country, she’ll need to get past an even tougher opponent — her family. Can Louise convince her dismissive older sister that she’s not a Zero anymore? Saito and Siesta get dragged along for the ride, and seeing Louise at home in her family’s extravagant palace makes them both rethink the crushes they’ve been nursing. With social status pushing Louise and Saito apart and raging hormones pulling them together, a love triangle like this can only end in explosions!

(Source: Seven Seas Entertainment)