Here's a ref pic for ya.
And to make that, I think construction paper might be best. <_< And what's good about that is, even though they're not durable, you can make two or three of 'em easy so if one rips or tears badly enough, you can put on another.
But yeah, red paper strip to start off with. Then take gold paper, write the kanji, then cut it out. If you can't find gold, you could always just write it on white. cut it out, then spray paint it. >_> Dry it out then glue it on. It'd work just as well, I'm sure.
And since you seem to have issues finding ref pics...I'll see if I can find a good one of the kanji on his armband...
Not PERFECT, but it may have to do...
Oh, and look! Here's the rest of it!
Though...by that cosplay in the second pic, it looks like he went hardcore and used fabric materials and embroidery... If you know how to do that, then go for it, but...xDD
Worst comes to worst......You can buy a full costume. >.>