Aqua

Aqua (アクア, Akua) is an original character created by Tetsuya Nomura. She first appears in Birth by Sleep and is the only female main protagonist of that game. She is voiced by Megumi Toyoguchi in the Japanese version of the game. Her name means "water" in Latin; along with her Rainfall and Rainstorm Keyblades carry a water theme similar to that of Kairi, whose name means "sea". Aqua is a level-headed and serious person, but often worries about her friends.

Aqua takes the Master Qualification Exam along with Terra and becomes a Keyblade Master. She is the last apprentice to be sent by Master Eraqus to seek out the missing Master Xenahort and Vanitas; Eraqus instructs her to bring Ven back to the Land of Departure and to watch over Terra, who has become vulnerable to succumbing to the darkness in his organs. After fighting Braig and then Ventus under Vanitas' influence, Aqua loses consciousness and she ends up at Yen Sid's Tower. Aqua returns to the Land of Departure with Ven's body, but soon realizes it's almost been completely wiped out. Using Master Eraqus' keyblade to remodel the entire castle, she creates Castle Oblivion to keep Ven's deceased body safe. Aqua then tracks down Terra to Radiant Garden, only to find him as Xehanort. Failing to bring Terra back to his senses, Aqua fights and defeats Xehanort. However, to save Terra's body from falling into darkness, Aqua saves him by sending her armor and Rainstorm Keyblade with him out of the darkness. Terra's body, along with Aqua's armor and Keyblade, are found in the Radiant Garden by Ansem the Wise and his apprentices. Her armor and Keyblade are placed in the Chamber of Repose, a room constructed by the six original members of Organization XIII under Radiant Garden, where they are visited by Xehanort and later Xemnas in his attempt to find the Chamber of Wakening. Aqua ends up in the Realm of Darkness; after the events of Kingdom Hearts II, she meets Ansem and learns about the chain of events that occurred in her absence and about Sora, the new Keyblade bearer. Knowing that Sora will come and rescue her friends, Ansem, and herself, she utters Sora's name with renewed hope.

Aqua's outfit has been altered three times as of October 2009. Since Nomura felt that the outfit she was wearing during the Tokyo Game Show 2009 was too revealing since her entire back is exposed when she jumps in the air, he modified her outfit to create a design that was neither too conservative nor too revealing.