The base garment is their school uniform. These three are freshmen who are trying to quickly rise to the top of the school by beating up people for one of the 4 Heavenly Queens off the record. It appeared to me that most of what they were wearing is BtSSB, but not being much into sweet myself, I could be wrong. What made me really happy is that the girl in pink--has a Bunny Bear! You can see it a little in the following screencap, as well as a head-to-toe of their outfits.