A Ballgag Collection

How could a girl her age walk around with this backpack is beyond you, it´s clearly made for a 4th grade girl.
This only made what was inside it, that more shocking.

First you stick in your hands to feel around as the sun isn´t giving you the best lighting. You feel a metal ball, then a hard rubber one, and a soft rubber one. You then feel some belts? Ok, this is getting weird. You grab one of the balls and pull it out so you can see. It´s a ballgag. The ball is blue with a nicely polished surface and white leather straps. You stick down both hands immediately and start to count the balls. 1, 2, 3, 4, ... 15, 16, 17, 18, 19! She´s gotta have her whole collection in that backpack!

After mentally digesting this you get a look at a tag in the packpack with her name and phone number, Kameko Musushiki.
So what now?