Disclaimer: I rate manga relative to other manga, so a 50 is average, 60 is a bit above, etc. Don't think that my 74 score means this is a bad manga- it's a great series that's more than worth the read.

Deranged Detective Ron Kamonohashi follows Officer Isshiki, a rather lackluster police detective. In the midst of a baffling case, he seeks out a private detective- the titular Ron Kamonohashi. Formerly the top student at an elite school for training detectives, Ron was cast out after the so-called "Bloody Field Trip" incident in which he was found at a locked room murder scene with all signs pointing towards him being the culprit. Ron himself remembers nothing from the incident, walking away with two things- a brand on his neck, apparently placed there during the period he doesn't remember, and (narrator voice) a burning desire to find the actual killer. Isshiki and Ron team up in search of the answer, solving mysteries along the way.

Unlike series such as The Kindaichi Case Files or Case Closed, Deranged Detective Ron Kamonohashi isn't entirely episodic. Though it follows a typical mystery manga structure of hopping from case to case, a lot of the cases give the reader more insight into the Bloody Field Trip case or actively work towards solving it. The author did an extremely good job of mixing the Bloody Field Trip incident into the story without sacrificing the quality of the individual cases, and uses it to have both individual criminals and overarching villains. It's honestly one of the best balanced mystery series I've ever read, both when it comes to manga and novels.
As far as the individual cases go, some of them are pretty creative with the tricks. Not too much to say about them, they're all pretty well done, and the pace of the deductions feels pretty good. I'd like to see more attempts at longer mysteries where there's multiple murders over the course of a few days, but I have a feeling that the story's heading in that direction now that it's established. Overall, no complaints with the story. It's a well done episodic mystery series with an interesting subplot.

When it comes to characters, the series has some really well executed oddballs. As you'd expect from the creator of Reborn, just about every character has some sort of tic or quirk that makes them stand out, but not to the point of being obnoxious. The dynamic between Ron and Officer Isshiki is really well done funnyman/straightman humor at times and an evolving friendship/partnership at others. It works really well with the series, particularly when the series is setting up cases rather than solving them, and often keeps the story lighthearted or provides comic relief. Deranged Detective Ron Kamonohashi isn't a comedy, but the duo provide some much appreciated funny moments throughout.
The side cast is also decent. Most of them don't especially stand out, but they have pretty solid characterization and a couple of them, particularly the instructors from the Blue, really help flesh out both Ron as a character and the mystery of his past. Some of them also have how they're presented evolve with the story and as we find out more about how they play into the Bloody Field Trip, which is a really cool touch. As for the villains, they're okay. Nothing particularly good or bad.

Don't feel like doing a full update, but after reading the ending:
Man. Damn shame. The majority of Part Two is absolutely top-notch mystery, the M. family plot takes full focus, and the overarching villain is engaging... and then the final arc has a bunch of reveals that aren't properly hinted at, the overarching villain's motivations and backstory get speedran, and the mysteries are a massive step down from the rest of the series. Oh, and then there's an absolutely absurd finish.
I still like the series, but it's disappointing to see it fall apart at the last possible moment.

The art in Deranged Detective is really good. It still has the cartoonish style that Akira Amano's previous works (Reborn, Eidlive, etc) have, but it's a huge step up and everything besides the characters has a more realistic tone to it that I quite like.

Combining episodic mystery with an underlying plot that keeps building upon itself, Deranged Detective Ron Kamonohashi is one of the best mystery manga I've read. If you're looking for striking characters, clever cases, and great art, this is the manga for you.