The Yazawa Gakuin - Fine Arts High School is the school which Mikako & Co. attend.
The name is taken from the president of the school ... no less than Ai Yazawa sensei herself! XD
In Gokinjo Monogatari she acts like she's the president of the school, a really strange kind of president. Very funny and unusual for a japanese people.
She thinks - and she wrote this in one of her corners into the tankubons - that japanese schools are too rigorous and serious. In the Yazagaku she sees her idealistic idea of the school: a place where boys and girls are helped and followed by their teacher.
In the manga, infact the students don't have to wear any kind of uniform: they are free to wear what they want to. (and not to be all the same look "like some rice meatball cut with the same shape" like Mikako says in the special chapter "Colorful")
That is because the school would teach to them to express theirselves in every kind of form they like: from strange way to wear - like Mikako - to the pure art - the beautiful artwork by Yuusuke or Tsutomu's photos.