Here's a little write-up on Nanami. There's probably some spoilers in there, but nothing that'll ruin the overall storyline of SKU. ;)

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Nanami Kiryuu is a character from the manga Shoujo Kakumei Utena by Chiho Saitou, which has been adapted into a 39-episode anime TV series and a movie. (I've only seen the anime, so I'll be talking about that mainly.) Her birthday is August 8th and is blood type B. Her voice actress is Yuri Shiratori.

Nanami is the younger sister of the school president, Touga Kiryuu, at Ohtori Academy. She's one of the most popular girls at school. Nanami has a big brother complex. She's in love with her brother, and hates the fact that he's one of the biggest playboys on campus. She gets jealous and upset when other girls get too close to Touga, and she often lashes out irrationally.

She is one of the elite students at the Academy to become a duelist who fights for control of the Rose Bride, who will in turn gain the power to revolutionize the world. Nanami becomes the acting school president when Touga becomes reclusive after losing a duel to Utena Tenjou.

Nanami has a dedicated follower named Mitsuru Tsuwabuki who is much younger than her, but is in love with Nanami. She basically uses him as a servant; he does whatever he tells her. She also has three female students (Keiko, Aiko, and Yuuko), who are basically her lackeys who do all of Nanami's dirty work.

Memorable Nanami moments include the time she tried to sabotage Anthy's room with snails, a snake, and an octopus. Her plans are foiled when Anthy already has snails, a mongoose (that eats Nanami's snake), and a giant octopus. Another great one is when Nanami thinks she lays an egg and, through unusual (yet very humourous) circumstances, becomes attached to it as if it were a baby. And lest we forget the time Nanami decides to wear a luxurious cowbell (which she thinks is famous brand-name jewelry) around her neck and refuses to take it off. Eventually, all her sentences end in "mooo!". She eventually turns into a cow, but Utena and Tsuwabuki change her back by taking off her cowbell.

There's just never a dull moment with Nanami! :D