Meet Louise, a budding magician. The students at the Tristein Academy call her "Zero Louise", due to her current record of zero successes with magic. In fact, her magic tends to go spectacularly wrong. Now, as an important test of her aptitude for magic, she must summon a familiar to be her servant. At this critical moment, she summons up all her magic and wishes for a familiar that is "devoted, beautiful and powerful", and gets... Hiraga Saito, an ordinary Japanese boy. It's difficult to say who is more surprised and dismayed, but the rules don't allow for second attempts. Louise is stuck with her strange familiar, and he with her.
Zero no Tsukaima: Futatsuki no Kishi
A normal high school student, Hiraga Saito, is transported into another world. The witch who summoned him is Louise. Although very cute, she is also very haughty and has no talent for magic. In fact, she is popularly known as "Louise the Zero" after the success rate of her magic. Before Saito could gain his bearings, Louise suddenly pushes her lips to his. Mysterious letters appear on the back of his hand and he becomes her familiar spirit.
So Saito begins to live with Louise in the boarding house of Tristein Magical Academy. Every day, he is abused, scolded, (and loved?) by this haughty but cute girl. This is how his exciting days filled with courage, humiliation, and love begin.