
This is my take on the story -
The characters live in a world where there is an illegal underground company that makes slaves by brainwashing people, I also assume the "taming" part is the seal of the brainwashing. Making the slave bound to the master for their lives. I assume thr slave can be made to do whatever the owner wants (from cooking and cleaning to erotic activities ( ° ʖ °) and anything else). The main character (Kanna) seems to have a deep connection with his fathers slave, but when his father dies the slave wishes to go with him. So Kanna wants one that looks similar to him but he will be his instead of his fathers. The cost of the slave is probably pretty hefty in price. One exchange for this is another person's life. Most likely giving them the same fate as the other slaves. I assume the injection bottles at the end have something to do with the beginning of the brainwashing process.
This story was pretty fucked up but also really interesting to examine this other world and how it works
If you're confused about the timeline of this story and which manga to read first, this is the order:
1. Azami
2. Sabita Yoru Demo Koi Wa Sasayaku
3. Renai-rubi no Tadashii Furikata (ch 4 - 6)
4. Hadakeru Kaibutsu
Have fun!