When we watched the episode of Durarara!! with the flashback of Izaya's and Shizuo's school years we were amazed, but also a little diappointed, because the uniforms were different. We liked the lightnovel version better, where they both had the gakuran uniform and Izaya and Shinra were in the same class. Also, Shizuo in black and red is just sexy :D
Anyway the idea of cosplaying those two demons from their school time was so alluring. They did so much shit, also Izaya was already such an asshole and Shizuo, I kind of took pity in him. But it's damn cool that Izaya was never able to get him down nor kill him. He's so amazing! We were and still are fascinated by their intense love-hate-relationship.
The costumes themselves were nothing special, but doing classical gakuran uniforms was nice and it may also be practical for other costumes to have them. Sewing them is easy and the fitting shoes were already there, because we used them for the Haruhi uniforms.