If you liked the Code:Breaker manga, the Anime-Planet community thinks you'd like:
The main character in Darker Than Black is similar to the male protagonist in Code:Breaker as they both have mysterious pasts and strange abilities. They are both part of another organisation of ability users.
The main character (Hei and Ogami) are very alike, what they are going through is alike too, the process of changing from an assassin in some way to a human with feelings.
in both manga the main characters start off as cruel and cold people but after being exposed to a series of events that will inevitably change their lives the audience finds out more about their background and the mysterious power dwelling inside each of them.
In Akumetsu and Code: Breaker we see two groups of people (mainly of high-school age) determained to obliterate evil. Both manga involve psychological and thriller themes and take on a sci-fi/fantastical bent. If you enjoyed one, you will likely enjoy the other.
Power corrupts, and absolute power corrupts absolutely. Top-ranked student Yagami Light is disenchanted with the world around him. Through a series of events, he comes into possession of the ultimate power over life and death: a supernatural "death note" which can kill nearly anyone at his whim. As Light sets off on a crusade-turned-killing-spree, investigators from a police task force try to stop the mysterious deaths - including Light's own father, a senior policeman.
Although the two series are very different, there is a similarity in the way the characters try to take the law into their own hands, to kill the criminals where they cannot be justified by law.
If you liked Samurai Deeper Kyo, you'll like Code Breaker and vice versa. Both being from the same mangak, you won't be surprised by the similarity in the design and the story telling. Both are about a young man at first looking like a dangerous person bearing an incredible power, but the main girl will be able to gradually change him and reveal that the main male isn't as bad as he seems to be. A lot of actions, awesome fights and great story telling.