If you liked the Death Note manga, the Anime-Planet community thinks you'd like:
On the eve of nobleman Oz Bezarius's fifteenth birthday, he and his loved ones gather to celebrate in a coming-of-age ceremony. But after Oz steps under a long-stopped clock and the hands finally move once more - thus fulfilling a mysterious prophecy - he is violently thrown into the legendary prison known as the Abyss by three cloaked intruders. Existing in another dimension, the Abyss is home to lifeforms born within its walls known as Chains; these beings can only live in the real world if they make contracts with humans, binding their power to the person's body. However, there's a catch - in time, the human will be overcome by the Chain's power and then thrown into the deepest level of the Abyss. When Oz wakes up in the Abyss he is quickly attacked by hungry Chains, only to be saved by one named Alice - a Chain who appeared just before he was thrown into the prison. Together, the two make a contract and return to the real world, where they are enlisted into the Pandora organization - a group researching both the Abyss and the trio that threw Oz into it. Along with members of Pandora, the duo searches to find Alice's lost memory fragments that are scattered throughout the world, to discover the secrets of the Abyss, and to determine if there's a way their contract can be broken without killing either Oz or Alice.
Kai Eto is the Narcotics Control Division's newest investigator and is quickly partnered together with cold, workaholic Hal Kurabayashi. Their job is to track down drug gangs and they must often work undercover in order to do so. While Hal efficiently locates and arrests his targets, Kai often gets too personally involved and acts based on his emotions rather than on common sense. However it seems that Kai is not all goodness and light, and when pushed to the edge he's taken over by a violent alter-ego which shows no mercy. With Kai and Hal's clashing personalities, opposing methods and secret pasts will these two rookies ever be able to cooperate, or will their inability to see eye to eye prevent them from ever truly working together?
Switch and Death Note are both capitvating detective/mystery stories (Death Note has more of a mystery theme where as Switch centers more around the police) with a dark side to them. To most of society Light seems like a normal, highschool genius, but behind the scenes he is actually Kira, with a goal to kill all criminals. To most people that know Kai Eto, he is a normal, happy-go-lucky kind of guy, but behind the scenes, he has a hostile alter ego that makes him nearly kill people. Both series though also have their little flecks of humor in them sprinkled nicely inside all the darkness and mystery going on. Light and Hal are also quite alike in the respect that they have no intrest in helping the criminals, only bringing them to justice. If you liked either one, you'd be doing yourself a huge favor by trying the other as well.
Both of the main characters in Death Note and The Melancholy of Haruhi Suzumiya have a desire to change the world that they are in. In Death Note, Light decides to change it in a drastic violent, way as opposed to Haruhi who wants to start over completely.