Fan Casting Aqua in Kingdom Hearts: The Series

Aqua's name is Latin for "water", while Kairi's name in Japanese means "sea". The only connection between the two is that Aqua met Kairi in Radiant Garden in Kingdom Hearts Birth by Sleep and put a protective spell on her necklace, which later brought Kairi to Destiny Islands. Kairi, by accidentally touching Aqua's Keyblade during this time, also inherited the Keyblade from Aqua. The official Japanese website refers to Aqua as the "Dancing Waters Forming Bonds" (絆繋ぐ舞水 Kizuna Tsunagu Busui).