 If you liked
Shi ga Futari wo Wakatsu made
|
 ...then you might like
Kimi no Knife
|
In both manga the main character works for a mysterious organization which involves killing. So if you liked the gore in UDDUP, then you might be interested in Kimi no Knife.
They both involve similar characters: a detective, a young girl with strange abilities etc; and give off a similar feeling.
They're both unique in their own way and have different storylines.
If you liked UDDUP then you will definitely like Kimi no Knife, and vice versa.