Going over the manga, it's based on the school uniform that Hiei makes the rest of Kongou's fleet wear. Some differences are the extended shirt side is on the opposite side, the stripes are missing on the other side of the shirt, and the collar ribbon is a bit simpler.
Hiei's outfit on the other hand is red in color. The shirt also doesn't come to a point down at the center, and instead spreads apart. The bottom of the shirt also lacks the stripes.
