Strangulation: Kubishime Romanticist(2002)

Now that he’s a cool college student, our anti-hero Iichan thinks his crime-solving days are behind him. Cynical, sarcastic and minimally engaged in his studies, Iichan is much more interested in his own feelings of disaffection and isolation. But despite his resolve to remain aloof, he’s pulled into the narrative when he encounters and bonds with a serial killer named Hitoshi Zerozaki – a homicidal maniac with the soul of an artist whose talent is on display at the grisly scenes of his crimes.

(Source: Kodansha USA)