For the up and coming concert, here's an idea of what the characters (that aren't in the band) are wearing. Also, a show of what characters are to be featured in the next chapter. Be excited. : )

Edit: I added a photo of what Hinata is now wearing in my mind (the first picture with a Toy Story T-Shirt), but the accessories of the second picture are the same. 

Akaashi Keiji

Yamaguchi Tadashi

Hinata Shoujo

Yachi Hitoka

Kiyoko Shimizu

Haiba Alisa

Tanaka Saeko

Matsukawa Issei

Hanamaki Takahiro