It's naturally unreasonable to expect a random high school dude would be good at kidnapping, mentally torturing, and breaking people, but since this is fiction, it could stretch the realism a bit. I mean, there's already a demon and teleportation involved, so why can't the MC show even a little bit of skill and insight? This is like reading a tennis sports manga, where by chapter 9 the MC still can't hit the ball enough to make it fly over the net. There's nothing convincing about how he's proceeding with the girls.
I'm sure the story will later present this all as according to keikaku (keikaku means plan), but it's still a poor decision from the author to make it feel all stupid, inefficient, and incompetent when it's happening.