|Age:||21 (TV series)|
|Home world:||Earth (Guardians of the Earth Timeline)|
|First appearance:||Seize the Light!|
|Last appearance:||Great Decisive Battle! The Super 8 Ultra Brothers|
|Number of appearances||50 (Series)|
|Family||Ritsuko Sasaki (Older sister)|
|Portrayed by||Ai Hashimoto|
As a child, Atsuko was very isolated from the society, as a result she turned to playing arcade games;something she found her solace in. At one point she possessed a doll named Lilia, which she lost sometime later.
As an adult, she joined XIG as an operator on the Aerial Base, and befriended Georgie Leland, an American worker and operator of XIG. Initially, she had a crush on Katsumi Kajio from Team Lightning but quit after he had a relationship with her sister. Atsuko always gave Gamu Takayama, XIG's analyzer and new recruit a cold shoulder, although she did show her warm side towards him, to the point where she broke her pen twice when sensing "something wrong" with Gamu while he was in Germany.
Once Again Gaia
Great Decisive Battle! The Super 8 Ultra Brothers
In this film, Atsuko was Gamu's co-worker whom supported him in his dreams. After Gamu's battle as Gaia along with his fellow Ultras against Black Shadow and their minions were over, Atsuko assisted him in creating Repulsorlift systems and converting a 150 year old ship into a spaceship where everyone makes their way to their universe's M78.
- Atsuko's personality towards Gamu is best described as Tsundere, meaning a person (commonly an anime character) who is initially cold and even hostile towards another person before gradually showing their warm side over time.
- Atsuko's doll, Lilia had reappeared again as a little girl by Psycho Mezard II in a plot to influence her. The monster's plan failed however, by her sister and Kajio's persuasion.
- In the end of episode 31 of Ultraman Gaia, Atsuko forced Gamu on a date with her after he was seen hanging out with Georgie at a restaurant in the beginning.
- Ai Hashimoto has retired from entertainment in 2001 but she reprised her role as Atsuko Sasaki in Great Decisive Battle! The Super 8 Ultra Brothers in 2008 once again.