Black Cat

Black Cat is a story about an ex-assassin who is trying to live a new life by being a Sweeper (people who captures criminal with bounties on their heads). Due to a certain event, Train Heartnet realized that killing is not the solution to some problems. He leaves the ranks of Chronos Numbers and began his own journey of being a sweeper . On the way he meets, Sven (also sweeper) and Eve (a nanomachine). Together, they traveled from one place to another working as Sweepers. They also aim on unlocking mysteries to Eve's real identity and relieving Train from his dark past. The series has kind of a new way of showing scenes in the story which I'm quite amused to. They like showing a character's current state first then show how it happened through flashbacks (like uhh... you see Train wounded then they insert scenes of how the battle happened before he was wounded). The series has a twisted plot with surprises in every corner. It's pretty action-packed too - it has neatly-done detailed battle scenes.  A pretty good anime to watch, although finding a copy or a good streaming site will be a bit of a challenge. -_-

Library War (Toshokan Sensou)

Library War is a masterpiece! It is one of my favorite anime. :D It is about a nation whose dissemination of information through books is controlled by the government. Libraries were obviously against this, so they adapted to a military-type of protecting a library. They can only rely on their Library Corps and a number of library laws to protect the libraries from being captured by the Media Enforcement Force. The main character, Iku Kasahara, is a girl who joined the Library Corps due to an incident that inspired her where someone defended her from the Media Enforcement Force when she wanted to buy a book years ago. She undergoes a militaristic training and became the first female member of the Library Corps Task Force. She faces trials and hardships as she works her way to defending libraries together with her comrades. This series is quite action-packed, it also has romance in the later parts. ;) I never got bored watching the anime, I even finished watching it in one sitting. Library War is definitely a must-watch. :D

Durarara!

Durarara is not your common anime. It's a story about groups or gangs clashing against each other. But there's this mysterious group called "Dollars" whose movements and numbers are unknown that seems to be gradually growing inside Ikebukuro. The series is quite unique because it shows the side of each person, showing how coincidences and events match for each, and another amazing aspect of the series - almost all characters are dynamic. But, it pretty much shows the sides of Mikado Ryugamine, Masaomi Kida, and Anri Sonohara. They are three friends who are somehow tangled up in a mysterious happening going around the town. Each have their own deep secrets not known by the other in the group. Also, I find it really cool in the series on how events that seem to be unrelated becomes connected to each other as the story goes on. There's also fantasy in the story - the headless biker, the cursed katana - which spices the story a lot. Though I sensed some (very few!) dull moments when watching the series, it was still bearable and I still enjoyed the whole series. I think Durarara's a great anime, so I recommend that you watch it. ;)