I'll be honest, I enjoyed the earlier chapters and was getting into the adult arc and all but all this stuff with the train has just felt too forced for me. I get that mental scars can do a lot and all but the sister had an idea about what could happen and was a full grown adult, yet still managed to get subdued and unable to fight back plus had an entire mental breakdown over night? I was willing to give lee-way for the girl to be super smart and all earlier on because ultimately she was coming off a bit of an adult level intelligence against kids, but now we've got less reason to believe that she had the resources on hand to pull something off (due to years without her memories) and the important part of explaining how she managed to break a grown adult who understood the full extent she was willing to go in about 6-10 hours just really stretches things to me. I get that we're shown signs of physical pain she endured but she's not at knife-point, in the middle of the street, where she could run away, scream, tackle the girl knowing that the guy will back her up, whatever.
For anyone who's enjoying it, I hope that you still have a good time, but it just feels to me like this story doesn't feel like 'earning' the pain and suffering we see in people and will just off-screen it to inflict mental scars and training that should have taken much longer to inflict for the sake of being able to keep the atmosphere.