Hmm actually thats strength~ Flexibility plays a part i suppose but what she is using there is strength~ Takes quite a lot of strength to have that amount of control so i would say that she is probably quite very strong...
Sorry to bother you again, Ryzen. This time's its just a normal reupload request. You might want to update it first to its v1.02, if you're not too busy. 炎のおっぱい異世界 おっぱいバニー学園