If I'm looking at it correctly, I assume she has her legs tied above her head, possibly left suspending. Possibly the greatest trick ever played on her.
Candy - Or else...Candy please, nanodesu.Trick or Treat!!My~
What cute monsters you are!But I'm sorry, I don't have any candy ready~So-in-that-case....You'll just have to play a trick on your Onee-san♡Amazing...To... to go so far...