Ryoko Asakura (朝倉 涼子)

At first, Ryoko appears to be a compassionate and hard-working high school girl. One of Kyon's friends, Taniguchi, places her in the top three first-year girls in the school with a grade of AA+: indicative of her pleasant personality, beauty, and athleticism.

Her enormous popularity made her the unanimous choice for class president of Kyon's homeroom class. She also showed particular concern about how Haruhi had distanced herself from the rest of the class.

However, it turns out that she is Yuki's backup, and as such, is also another "humanoid interface". Much like Yuki, she finds it difficult to empathize with humans, but unlike Yuki, possesses exceptional social skills.

Initially she cheerfully supports Kyon's reaching out to Haruhi, often encouraging him to "open her up to the class," making Haruhi easier to observe. However, she later decides to try and kill Kyon with a combat knife in the hopes of catalyzing an observable reaction from Haruhi.

Her efforts are stopped, after Yuki defeated and removed her from the physical world. It's interesting to note that her cheerful personality doesn't falter, even at the moment of her own demise. Afterwards, Yuki fabricated a cover story that she moved to Canada. Ironically, the death/disappearance that provoked Haruhi's reaction in the end was Ryoko's own.

Ryoko makes a reappearance in volume four, on an alternate timeline in which Haruhi never attends North High or forms an SOS Brigade.