Koyori the scientist of the secret society. I'm pretty sure she is broking most lab safety protocal possible there which lead to a conclusion that either she's just playing around or she's a mad scientist in a disguise of cute anime coyote girl.
Overall, Koyori's outfit is not too hard to make a replica, but still there are lots of detail to make. And her pink theme may be quite difficult for me to pick the right color.