Zero no Tsukaima Chevalier
Hiraga Saito was summoned to the wonderful world of Halkeginia through the use of magic. He was summoned by the very cute, yet with "Zero" magical ability, Louise. Although it was an accident, Saito was summoned during the summoning ceremony, and sealed the agreement to become Louise's "Familiar" through a kiss. That is how he arrived in this world.