Kodona is literally the boys solution to the popular japanese 'lolita' fashion. It involves wearing a style similar to what victorian boys wore. Including masculine blouses and shirts, knickerbockers, short trousers, knee high socks, top hats and newsboy caps. This is also what some girls use when they don't want to dress 'up like a victorian doll'.
Just google image search 'kodona' or 'oujisama' for images