Appeared before Naked Snake during the 1964 Operation Snake Eater as a cooperative KGB spy sent by Soviet leader Khrushchev. Her mission was to supply him with information and acquire intelligence on Shagohod.

She donned glasses and the alias Tatyana and approached Shagohod developer Sokolov. After Sokolov was captured by Colonel Volgin, she pretended to serve Volgin. After rendezvousing with Naked Snake, she uses both her identities as EVA and Tatyana to assist Snake on his infiltration mission and lead him to the massive fortress Groznyj Grad. There, after hearing The Boss's true intentions, she tells everything to Naked Snake in the form of a debriefing on The Boss.

EVA's true identity was a child ofthe Philosophers who remained in the People's Republic of China. Since childhood, she had received spy training in The Boss's Charm School, and eventually joined the Chinese People's Liberation Army General Staff Headquarters, Second Division. There, she learned techniques such as "bandit shooting", a horizontal sweep using the Chinese pistol. She took the place of the real EVA sent in by the KGB during Operation Snake Eater and attempted to steal the Philosophers' Legacy, a stockpile of the three superpowers' capital, for China. She stole microfilm containing the location of the Philosophers' Legacy that The Boss had recovered, and returned with it to China. That microfilm, however, proved spurious, and the real article fell into the CIA's hands. Chased off by the Chinese government, EVA fled to Hanoi in the 1970s and disappeared.