At first glance, Ryouko Asakura, a fictional character in the Haruhi Suzumiya universe, appears to be a model student. She sports dashing looks, outstanding athletics, is amazingly smart and her friendly nature make her very popular with the girls of her class. In a dramatic turn of events however, she reveals herself to be an alien-made humanoid, willing to resort to murder in order to provoke a reaction from her observation target, Haruhi Suzumiya.
Ryouko is a freshman at 'North High' high school and classmate of both Haruhi Suzumiya and Kyon
. Her ever-cheerful personality and impeccable academic knowledge prove especially highly regarded among the girls of her class (except for Haruhi) while her gorgeous looks make her equally popular among the male students. Taniguchi, a classmate and friend of Kyon's goes as far as to rank her a AA 'plus' on his A to D scale of all the first-year females, putting her in the top 3 of his list. She is soon elected class president and as such, is constantly trying to reach out to the reluctant Haruhi, who quickly distances herself from the rest of the class. As Haruhi starts to open up to Kyon during their daily conversations, Ryouko encourages him to pursue this relationship, asking him to relay important, school-related matters to Haruhi.
A couple of weeks into their first semester however, Ryouko anonymously asks Kyon to meet after school, where she reveals herself to be an artificial, humanoid interface created by an alien being called the Integrated Data Entity, similar to Yuki Nagato
albeit with infinitely more sophisticated social skills. Initially installed as Yuki's backup to observe Haruhi, Ryouko grows weary of Haruhi's stagnating state of mind and decides to try and stimulate an observable reaction by stabbing Kyon with a knife. Like Yuki, she displays extraordinary powers, manipulating the parameters of her environment to her will, for instance by closing off and transforming the entire class room and its equipment or putting Kyon in a state of stasis. Her plans are ultimately foiled when Yuki manages to breach the barriers of her alternate dimension and installs a cancellation program, dissolving Ryouko Asakura into nothingness. Even while effectively dying, Ryouko never loses her cheerful, calm personality, even warning Kyon that a change of heart within the Integrated Data Entity could still be a threat of his life. In an ironic turnaround, the demise of Ryouko, which Yuki masks with an unexpected, sudden move of Ryouko's family to Canada, brings about the reaction Haruhi's, Ryouko had so much desired.
Ryouko makes a temporary return in The Vanishment of Haruhi Suzumiya, the forth novel of the series, where Kyon suddenly finds the world transformed into an alternate dimension with no signs of Haruhi and the other SOS Brigade members being regular humans, or in the case of Itsuki Koizumi, missing as well. All of her cheerfully friendly characteristics are kept intact in that reality and she is friend and neighbor of Yuki Nagato, the sole member of the school's literature club.