The Rabbit Team girls in the background are drawn in such a simplified style that I can't tell if the one with brown hair is Azusa, Saki, or Karina.
If we are basing it on the hair color, she might be Karina but she is shorter that Aya if we are basing it on their height on the pic. Azusa is a little taller that Aya so it might be Azusa. I’ll just put Azusa for now until we get a 2nd opinion. I’m also basing it on the fact that they are together in the M3 Lee along with Saki(she’s out because of her hair color and she rarely seen conversing with the other Rabbits).