|“||Two-headed serpent spy.||”|
— Official description
A member of intelligence bureau of the special force. She was on a mission to infiltrate the Terrorist group. Her mission was later revealed by another agent when she was trying to look through the confidential documents about ARA and had to flee back to her country. She joined the Counter-Terrorists in hope that one day she could get her hands on the documents again.
She also appears in the Z-VIRUS trailer, investigating a lab. Suddenly, Sting Finger appears and attacks her from behind. She tries to escape and encounters a Venom Guard. Fortunately, she gets an M32 MGL on the ground to defend.
- Female Researcher - Choi Ji Yoon's sister who had turned into Sting Finger zombie during the escape of Rex Research Institute.
- Singapore/Malaysia: 21 September 2011.
- Indonesia: 4 January 2012.
- Turkey: 24 July 2013.
- CSN:Z: 16 December 2014.
- Vietnam: 23 April 2015.
Zombie Scenario Stats
She has black short hair tied up, her hair bangs almost covered one of her eye, her eye color is brown.
She wore a pair of glasses, pair earrings, dark blue coat with matching mini skirt, unbuttoned white shirt, revealing a her bra and a butterfly tattoo on her left breast, silver watch on her left arm, tights, and a pair of black high heels
- Three alternate skins for this class exist, being Soccer, Limited Edition, and Transcendence
- In the selection icon and the manga, Choi Ji Yoon has brown hair but in-game, her model shows she has dark blue hair.
- She appears as a Non-playable character in Chaos chapter in Zombie Scenario: Season 1 and Episode Choi chapter in Zombie Scenario: Season 6 to support players.
- The NPC picture is similar in Counter-Strike Online 2.
- There is a blue butterfly tattoo on her left chest. However, it does not shows up in Manga.
- In Counter-Strike Online, she is seen wearing white undergarment, while in Counter-Strike Online 2, her undergarment is black in color.