Deadman Wonderland

Deadman wonderland was originally a manga series published in 2011 and also aired the anime during the same time. However, the anime was not as popular compared to the manga so they only have 12 episodes in the season and 13 volumes for the manga. I really liked how crazy this anime was, from the start to the end. The plot and ideas are interesting and different, I was hooked after the first episode. It left you wanting more! Its about a prison that is also a carnival for people wanting some entertainment and it is called, "Deadman Wonderland". For the main event, inmates fight eachother to the death using everything they can in their power. The main character was framed in killing all of his classmates at once by a mysterious man that showed up all of a sudden and he ended up at this prison. He was the only one who was spared to live. There is a reason why that he was spared... 

It is super mysterious with lots of twists and turns. I watched all 12 episodes in a few hours, but was deeply disappointed that they didn't finish the anime. The season ends with no conclusion. I recommend it but if you don't like cliffhangers don't watch it. Unless you're willing to read the translated version of the manga to know what happens next.