STN is a secret organization charged with capturing witches of all ages who misuse their inate ability of the Craft. Its newest recruit is a young girl named Robin, who wields the same power that she is helping to control. While skillful at their ability to detain quickly, the number of witches keeps seeming to increase, and the misuse of power grows stronger, casting a shadow of doubt as to what is really going on. For STN, there is much work ahead, and for Robin, her troubles are just beginning...
Murao Mima has created a robot daughter named Key, but after raising her for a very short time, Mima dies, leaving behind cryptic messages telling Key how she can become human. Key must struggle alone to learn the harsh lessons of life and search for the 'key' to her own dream: the power of 30,000 friends to make her a real human girl.
I can't really say why these two are similar without spoiling a lot.. but let's just say that their plots become rather similar towards the ends. Plus both are quite dark and interesting.
Psycho-pass has technology, and Witch Hunter Robin has magic, but they both are fairly dark, gritty takes on the police procedural genre, and both show the depths people can sink to when they have power.
When police organizations use a member of a group to hunt down other members of that same group, things always get interesting. The plot of these two anime revolve around the drama that is created in exactly that situation, and offer a dark take on questions of right and wrong.
Sumiregawa Nenene is an author who hasn't published a book in years. However, at a book signing in Hong Kong, things go fascinatingly awry. For starters, her guides are three sisters who operate a detective agency: Maggie, Michelle, and Anita. Then there's the attacks on Nenene's life, and her only line of defense is the three sisters -- who can all use paper as weapons, tools, and even transportation. But can their powers protect Nenene from the mysterious forces that not only want her, but all the precious books of the world...?
Both these series have young protagonists caught in situations that they have to think their way through. WHR is considerably darker, while ROD TV is more light-hearted. Both deal with secrets, government and uncanny abilities.
In an experimental city of despair and carnage, ORGAN will do anything necessary to gain power and wealth. Unfortunately for one underground boxer who was mutilated, a rogue doctor has given him what ORGAN specializes in and he despises: Texhnolyze body parts. Will these cybernetic appendages help exact his revenge upon the one who made him this way?
In a post-apocalyptic future, Abel Nightroad does occasional dangerous work for the Vatican, to whom he is extremely loyal. While the apocalyptic war has long been over, humanity is still entrenched in a shadow war against the vampires. Lady Catherine, the leader of his operations group "AX," seeks to prevent a renewed full-scale conflict, but there are many forces on both sides bent towards war. As Abel and the rest of AX try to stop this, he encounters a young girl who will be the key to humanity's survival or demise. Now, Abel must not only fight for humanity, but also try to face his regrettable past...
Trinity blood and WHR are very similar. Both are about an individual fighting his/her own kind for the sake of mankind. Both seem to be episodic or monster-of-the day kind of series but eventually both unfold a story. And finally, in both series the enemy, that is so obvious in the beggining is not so obvious in the end.
Both Trinity Blood and Witch Hunter Robin follows members of a team that seeks to protect ordinary humans from dangerous beings. Add a few secrets, a scheme or two, and you'll see their similarities.