Aya Brea is the central character and main protagonist of the Parasite Eve video game series developed by Square Enix. The character first appears in the 1998 role-playing video game Parasite Eve. In the game, she is a rookie NYPD officer who faces off against Eve, a being created by sentient mitochondria wishing to conquer life on earth. In the 2000 sequel Parasite Eve II, Aya, now working for the FBI, is investigating further activities involving mitochondria. In the 2010 game The 3rd Birthday, an amnesiac Aya is found by the Counter Twisted Investigation unit to fight against the "Twisted", a mitochondria-spawned creature that has taken over Manhattan. Created by Parasite Eve '​s producer Hironobu Sakaguchi, she was designed by Tetsuya Nomura after her original artist failed to realize Sakaguchi's vision for the character. Nomura ended up blending two different character designs to create her final appearance. He also returned to design her in the two sequels, although she was mostly designed by another unnamed artist for Parasite Eve II. Her depiction in The 3rd Birthday was meant to be both realistic and attractive. The character has been well received by critics.