Can u name some titles?
I don't know how to search for authors here
I've read Harada's work too. It can get intense. Here's a good start: Yatamomo by Harada
Ty. I will save these for another day. I've had my fill of to***xity for this entire week. !!! It wears the soul.
Here's one that has similar premise as this story (kidnapping&confinement): Gintama dj - Mienai Kusari
If you are fine with reading fanfics you can go ahead with this one. It is also a short story but the delivery of the plot is really good. Just be aware that it can get more disturbing, disgusting even, as compared to "Tosa's Master".
I've read a lot of manga/hwa/hua with similar premise of confinement and mind break like this one but personally speaking, nothing beats Harada sensei's mangas with these type of stories. It's not about how dark the story is, but the process on how the aggresor slowly breaks into the victim's mind, this is what I find lacking in most stories, just like this one.