Both of these shows focus on young, aspiring detectives, though the detectives in Tantei Gakuen Q have more noble motivations. Both of these shows are full of humor, which makes you forget that there’s real danger out there for the main characters—until they come face to face with it.
It has the same genre minus the age of characters in the story. Tantei Gakuen Q's characters were Kids, in Bloody Monday, it's adults.
There is the same concept of a student following the aspect of being a detective. Yamada Ryosuke is also one of the supporting student detectives, and there is a similar amount of suspense.