She is the Suzumiya Haruhi of Strawberry Panic, without the hax powers or the in-your-face "flamethrower of joy" irresponsibility. She is the student council president for St. Lelim, one of the 3 Catholic academies on Strawberry Hill. She pulls off Haruhi-level competence and grandeur, the latter selectively, in that often she prefers to put someone else in the spotlight instead of herself. Out of deference to her talents, she was asked to play the lead star role (Carmen) in the combined school play (cast picked from all 3 academies). In addition, she was given the task of preparing all the costumes for it - while still keeping up with student council work. In her off time, she's the president of the Cosplay club, the Secrets Investigation club and whatever other club she wants to set up. In short, she has her own SOS brigade.
In personality she is perhaps closer to Tsuruya instead of Haruhi. She is a mysterious yet friendly warm onee-sama you can always look up to. She can keep a straight face while pondering on the tedious predictability of how student council meetings degenerate into a bickering fest, hence likes things that bring fresh changes to routine. Occasionally, she pulls out an outrageous side, usually only to her own not-SOS club. Incidentally, one might be puzzled at the lack of romance with Chikaru in a show that is blatantly filled with shoujo-ai (and outright, almost-off-screen yuri). In fact, she has her moment of romance three years ago, and you can refer to the Lelim Drama CD for more information.