I haven't been able to figure out if the blue haired girl in the first frame is a random extra or some character from one of Kotobukiya's product lines. She doesn't seem to match anything on their web site. She does have pretty hair though!

The way that Seira is talking reminds me of one the personas that Ai Hayasaka uses at school. In the 3rd frame it seems almost like Koyomi thinks Seira is trying to bum lunch off her or something. I don't quite get the joke there.