School Uniform
As you've probably noticed, the Threelights do not wear the regular Juuban High school uniform the other male students wear. We never actually get to know why on Earth the three get this special treatment, but hey, I'm not complaining as I really like their special uniforms.
The Threelight's uniform is a two-piece suit made out of a dark blue material. The pants are simple pants that go with every suit/uniform, the jacket is long-sleeved. As Seiya (as well as Taiki and Yaten actually) never takes off his jacket, we do net get to know what he wears beneath it. The jacket itself has a low collar that is a lighter shade of blue than the rest of the suit. In the middle of said collar is a small yellow star.
Instead of using buttons, the jacket opens and closes using a zip. A small zip is also on each of the jacket's sleeves. The jacket has six pockets alltogether, three on the left and three on the right side of Seiya's upper-body. They too close and open with zips and have a "border" made of the same light blue material as the collar. The shoes Seiya wears are black; in some anime episodes we also see that he wears white socks (actually a big no-no with a dark suit, tsk tsk).
So, in my opinion it's a very nice school uniform, that has a classy and trendy side to it at the same time. I like it. ^____^
The Red Suit
The red suit is Seiya's other main clothing apart from the school uniform. Seiya usually wears his red suit when he is up and about as the popstar Seiya.
The suit, as you can probably guess, is made from a bright red material. It is a two-piece suit; the pants are simple pants of the sort that go along with every suit, the jacket is long-sleeved. Seiya always wears a dark green (yes it's green, not black), long-sleeved dress-shirt along with this suit. A special feature of this shirt is that there is a round accessoire attached to each sleeve. This accessoire looks to be a round jewel of some sort, which I personally believe to be some sort of cuff. This cuff is dark blue in color and embedded in gold. The tie he wears is yellow. The jacket itself uses red buttons to open and close; there are four red buttons on each sleeve as well.
The shoes themselves are red as well, and most likely made from leather. I have to say that they are honestly the one thing I don't like too much about this outfit. But then again, maybe black shoes would have looked even weirder with such a bright red suit.
Sport Clothing
Are you ready to face the dark side of the force, young Jedi? If not, go as long as you still can, GO!
Yes, Seiya's sport clothing. It's supposed to serve a certain purpose (you know, you should be able to move well, and well, yeah, stuff like that), but it is undeniably evil. We are doomed to see the cursed outfit in episode 176 and for a short moment in episode 177 once more, but those were two episodes too many.
Let's start at the top once more, so in this case with the hairband (and what a bad start it is already). Yes, Seiya wears a red hairband. An image of Seiya with a red hairband also appears in the Material's Collection, and Naoko Takeuchi notes on it that that Seiya sometimes wears it while doing sport.
Seiya is wearing a cropped blue shirt. The shirt itself is sleeveless and stops somewhere below his ribcase; it also seems to be very loose, as there's always a huge gap in-between the shirt and Seiya's chest. The pants he's wearing are white leggins that stop at the knee. >_< Ouch. On top of the pants he's wearing brigh-red briefs. >_<;; Double-ouch.
He's also wearing black slippers (they look like ballet slippers to me) and bright yellow legwarmers that go from his ankles up to mid-thigh.
What an outfit ...
Seiya looks spectaculary good in it - don't even try to deny it. The uniform in itself is quite simple though; Seiya is wearing a short sleeved powder-blue shirt, choosing to leave the top button unbuttoned. The shirt has two breast-pockets, buttons up with black buttons and is tucked into the pants he is wearing. Along with the black pants Seiya also wears a black belt; his shoes are black as well.