Darker than Black DARKER THAN BLACK -黒の契約者- (Dākā Zan Burakku -Kuro no Keiyakusha)

Alternative Name: DARKER THAN BLACK -黑之契約者-

                                       (DARKER THAN BLACK -Hēi Zhī Qì Yuē Zhě-)

Genre: Sci-Fi, Neo-noir, Supernatural, Action, Drama, Mystery, 

               Psychological, Assassins, Conspiracy, Crimes, Fighting, 
               Polices/Detectives, Superhuman, Superpowers, Adventure,
               Gunslingers, Twins, Post-Apocalyptic

Description: 

In Tokyo, an impenetrable field known as "Hell's Gate" appeared ten years ago. At the same time, psychics who wield paranormal powers at the cost of their conscience also emerged. Hei is one of the most powerful of these psychic agents, and along with his blind associate, Yin, works for one of the many rival agencies vying to unlock the mysteries of Hell's Gate.

Episode

Season 1: 25 episodes + 1 Special 

Season 2: 12 episodes + 4 Special

Original Run

Season 1: April 5, 2007 – September 28, 2007
Special: March 26, 2008

Season 2: October 8, 2009 – December 24, 2009
Special: January 27, 2010 – July 21, 2010

Studio: Bones

Darker than Black: Gemini of the Meteor 
DARKER THAN BLACK-流星の双子- 
(Dākā Zan Burakku -Ryūsei no Gemini-)

Alternative Name: DARKER THAN BLACK -流星之雙子-

                                       (DARKER THAN BLACK –Liú Xīng Zhī Shuāng Zǐ-)

Description: 

Two years have passed since Hei and Yin escaped the Syndicate after the events of the first season. Making their way to Russia, Hei encounters a young girl named Suou Pavlichenko, whose family is gradually pulled into the war between contractors and various intelligence factions. Meanwhile, Misaki Kirihara has quit her position in Foreign Affairs to begin her own investigations into Hei, the Contractors and the Syndicate.

List of Songs (directly to CrimNight Muse Garden)

1. Howling                                    [First Opening]

2. Kakusei Heroism               [Second Opening]

3. Tsukiakari                                [First Ending]

4.  Dreams                                 [Second Ending]

Season 2:

1. Tsukiakari no Michishirube        [Opening]

2. From Dusk Till Dawn                      [Ending]
3. Twinkle Real Star                              [Insert 6]
4. Kanashiki Yume no Maki            [Insert 12]

Special:
1. Darker than Black                     [Ending]

Manga

1. Darker Than Black: Kuro no Keiyakusha

Published: February 24, 2007 – November 28, 2007

Volume: 2

2. Darker than Black: Shikkoku no Hana

Published: May 15, 2009 – January 21, 2011

Volume: 4

Here is the preview:

Season 2: