I'd say this: curiosity kept me reading for the first few chapters. Before I knew it, I've read through quite a few more and was enjoying it.
That aside, I really don't know what would be considered cliché or overused in such genres yet it still felt rather unique. The story unfolds really smoothly and at a good pace, not to mention the writing style: the elegant flashbacks/rewinds were extremely appealing.
The plot itself, even for a mystery, was not very expected (for me at least lol) and so, the small surprises along the way were pleasant from a literary viewpoint.
Romance though? Nah, not much. Interestingly enough, the romance, served the plot very well and doesn't feel like it was a forced addition or just thrown in for the sake of it.
Fight scenes are essential for the crime part right? There is plenty of those and they all are well drawn. Like everything else, they served the plot without feeling over-done or just... tacky.
To keep this short and sweet, Koroshi Ai is a very satisfying series both literarily and artistically. The entire story resonates well with all its elements, is consistent and gripping.
