Age: 16-18 during course of the show
She is a Lucky Star Character associated with StriderTuna for his unrelenting idolatry of her.
She's a smart, beautiful, nice girl who's always willing to help (But she's so nice Konata feels guilt for asking her for help; though it doesn't stop the smaller girl from remarking on her figure)
She's known for being the curviest girl (though the art doesn't show it well for the most part), being a human Wikipedia.
She was one of the few characters shafted out of air time in the anime by KyoAni's focus, something StriderTuna complains about at times.
Tuna's reasons for liking her: Beauty with curves and cuteness, brains (most attractive trait), and a nice amount of moe.
Generally any topic on OT that involves Miyuki heavily will have people saying "inb4 StriderTuna" due to the fact he will have something to say on the subject. Also bashing her is a clear provociation of StriderTuna. (Mainly for the fact there's not much worth bashing, and as StriderTuna would say "You're a Konami/Kagami fanboy if you bash her")