3 words: Classically addictive CLAMP
I love this show because it's just cheeky enough to be fun, just enough plot twists to keep you guessing, just enough character development to draw you in, and just pretty enough to really enjoy in HD. I watched a random episode in the middle of the series while in Japan (and no, I don't speak enough Japanese to know what the hell was really going on) and knew right away I'd have to buy it when I got home.