this anime has recently started last april and certainly has the potential to give Death Note a run for its money. XD the story's pretty complicated, but if you stick to it, things eventually make sense.
Here's a summary of what I understood so far:
Ten years ago, an impenetrable field called "Hell's Gate" appeared in Tokyo. A week after it first appeared, beings with special abilities called "Contractors" appeared. They have absolutely no conscience or human emotion and kill people in cold blood. The main character in the story is this masked figure called "Hei" who battles these contractors in the pursuit of unlocking the mysteries of "Hell's Gate". Ironically enough, he happens to be a contractor himself. During the day, he is Lee Shen Shun - an ordinary student who works part time and came all the way from China. He is kind and compassionate to people, but merciless to his enemies.
He reminds me of L from Death Note. Similarities include the hair, the eyes (sort of) and the appetite. Heck, the series reminds me of Death Note - the way the plot thickens, twists and unravels and leaves you stunned at the outcome. I highly recommend you guys watch it.