The slavery collar was a relatively inexpensive magic tool made to be placed on the neck, but it seems that that the slave would die if they removed the collar by themselves after being contracted. The magic from the contract would kill them if they removed it without permission. Scary! Contract magic is scary!
Then, if the wearer of the collar injured its master, it would strangle them to settle down their rebellious heart. Strict as hell.
Furthermore, the collar could tighten just by the master thinking about it. It could also be used to lightly strangle them when they are called, for example.
And suitably, it costs money to release slaves… yep, troublesome!
“Well, in that case I’ll register then… let’s deal with troublesome things first.”
“Yes, please fill the magic stone in the collar with magical power… umm, then to check if the registration worked properly, please lightly strangle me.”
Fill it with magical power to register… Yeah, I felt the path connect. I’m probably registered with that.
Then, though I was reluctant, I imaged her thin neck be tightly constricted.
“Hu-, e-…!”