Btooom!

Ryōta Sakamoto is an unemployed 22-year-old who lives with his mother. In the real world, there may be nothing really special about him, but online, he's one of the world's top players of the combat game called Btooom!. One day, he awakes in what appears to be a tropical island, though he has no memory of how or why he has come to be there. While wandering around, Ryōta sees someone and calls out for help. The stranger responds by throwing a bomb at him. Ryōta soon realizes both that his life is in danger and that he has somehow been trapped in a real-life version of his favorite game.

I didn't expect to, but I really enjoyed this anime. If you like Sword Art Online, you'll like this. It combines the real world and the game world together to create a life-or-death story where the protagonist is just trying to survive and make it home.

The Mystic Archives of Dantalian

This story takes place in England just after world war 1. After the death of his Huey receives a mysterious key and according to his will, must take custody of the Bibliotheca Mystica de Dantalian in order to inherit his estate and all his possessions. Upon meeting Dalian, a child living at the estate, he learns that she is the guardian of the Archives which contain forbidden knowledge stored in thousands of magic books called "Phantom Books"

Just started watching this and I love it!

Another

Another is about ghosts and mysterious deaths!

Plot: Recently transferred to Yomiyama Kita Middle School, Kouichi Sakakibara gets the feeling something isn't quite right with his class, who all seem to be afraid of something. He finds himself attracted to the strange yet beautiful girl named Mei Misaki, but his efforts to get closer only complicate things further. 

Aria the Scarlet Ammo

Kinji Tōyama is a student at Tokyo Butei High, a universal educational facility. At this school, students undertake special training in order to learn the path of the Butei, which is a national qualification permitting its holders to arm themselves and capture criminals. The Butei were established to counter the worsening crime conditions, with training in various specialized fields. One day, Kinji decides to quit the Academy, until he is mysteriously attacked by the Butei Killer, a notorious criminal hunting down Butei with a passion. The elite Assault prodigy Aria H. Kanzaki comes to his rescue. From this point on, Kinji's future as a Butei changes drastically.

I enjoyed this anime a lot. It was filled with sarcastic humor, some mystery, and lot of action. Definitely landed a spot as one of my favorite anime I've seen.

Blue exorcist

The story revolves around Rin Okumura, a teenager possessing abnormal strength and endurance who, along with his twin brother Yukio, was raised by Father Shiro Fujimoto. One day, Rin learns that he is the son of Satan, the strongest of all demons. The rest you have to watch ;)

Hitaraku maou-sama

In another dimension, the Dark Lord Satan and his forces of evil are defeated by the Hero Emilia Justina. Satan and his Demon general Alciel are forced to flee through a portal which drops them off in modern day Japan. With their magic slowly depleting in an unfamiliar world, they are forced to act as normal human beings in order to survive. As the Hero Emilia Justina follows them through the portal, she too is met with the same circumstances, and although she still harbors negative feelings towards Satan for his past acts of evil, they become unlikely allies in order to survive. 

This anime keeps you constantly laughing, I loved it and I think you guys will love it too

Inu x Boku SS

The Maison de Ayakashi, better known as the Ayakashikan, is a high security apartment building where humans with demon ancestors, youkai, reside, each guarded by their own Secret Service bodyguard. A youkai girl named Ririchiyo Shirakiin moves into the Ayakashikan hoping for some peace and quiet. Instead, she finds herself with the service of the Secret Service Agent, Soushi Miketsukami. Miketsukami slowly helps Ririchiyo overcome her social awkwardness and be nicer towards people.