I recently finished Monster which is now one of my favorite anime of all time. A synopsis spoils the first 5 episodes so if you're interested in intense psychological thrillers give it a look. I don't think I've ever gotten so many chills watching an anime. Despite monster honestly being a masterpiece some people probably won't enjoy it due to some parts that can be considered slow, a 74 episode length, a complex story and animation from 2004. Anyways if you have enough time on your hands you should absolutely check it out.