I was initially attracted to this story by the cover art and blurb. I liked the idea of an Isekai novel focussed around taming. However, I got to the end of chapter 4 and decided this story would not be my thing. I probably should have paid attention to the content warning in the blurb. I'll give a review for this anyway as the author has asked for feedback and encouragement to keep writing beyond prototyping. Here goes, based on the start of the book, anyway:
The writing style for this story, I feel, suffered a little from too much exposition. I believe the author wants to develop a rich world to set this in, but quite often I felt that characters backstories were told to me, rather than a more "organic" reveal through dialogue and description. I did find this to improve quickly as the story went on, however.
I can't contribute much to the story having read only a quarter of what's available. What I did read was interesting and not something like I've read before, which is a difficult element to Isekai stories on RRl as there are so many amateur authors beginning stories to write on the site. This one stood out, so take that as a recommendation if the events that start at the end of chapter 4 are your sort of thing.
The sentence structure for The Tamer Is Repulsive is good. There are only a few stylistic errors --nothing an auto-corrector would pick up-- that sometimes result in sentences that are a bit unwieldy in the amount and order of information they deliver. I'd also say that the author uses a decent mix of passive and active voice, so you aren't stuck with monotonous pacing. One criticism I would like to offer is that the author tends towards sentences of similar length (usually longer). I would have enjoyed a discerning use of shorter sentences in scenes of action (such as when his tamed ratgirl saves him from execution).
Like story, I haven't had much experience with the characters. I have the same feedback that I had for style, however. Too much exposition. Beyond that, the characters haven't yet shown anything wrong with them. I did find the ratgirl's manner of speaking a little grating and too-similar to the trope of catgirls in other stories... but the author can write in whatever tropes they please, my feelings be damned.
Keep going ianisomega. Once this gets beyond prototyping and you've settled into your writing style, people that like this genre of story will love your story.