Manga Review: DETECTIVES THESE DAYS ARE CRAZY! is a manga that hits different when you’re no longer the kid

Detectives These Days Are Crazy, Vol. 1

Story & Art: Igarashi Masakuni
Publisher: One Peace Books (Print & Digital)
Publication Date: April 28, 2025
Rating: Teen
Genre: Manga, Comedic Drama

Behold, a great detective who thrills the world solving impossible cases in no time! His name? Keiichiro Nagumo.
…But all of that was over a decade ago. Now he’s just your typical middle-aged dude. Nagumo is behind the times to the point that he doesn’t even know what a smartphone is. But out of the blue, he is confronted by a high school girl named Mashiro who shows up wanting to be his assistant. Witness the miracles a gender-gap detective duo can make!

This review contains spoilers for Detectives These Days Are Crazy, Vol. 1. I received a free copy from One Peace Books in exchange for a review.

Detectives These Days Are Crazy follows the once-great detective Keiichiro Nagumo, now your average middle-aged dude so behind the times he doesn’t even know what a smartphone is. (HOW?) He meets a high school girl named Mashiro who wants to be his assistant, and the duo certainly makes for an exciting pairing.

The manga opens with Keiichiro dreaming of his heyday before reality sets in. These days, he’s just a 35-year-old nobody running a detective agency that can barely cover rent. He laments that people used to praise him in his youth but now criticize him for losing his abilities. The truth is, he hasn’t lost them—he’s just not as young as he used to be. (Mood.) As he prepares to head out on his first investigation in a while, he opens the door to find Mashiro, a clearly airheaded high school student who’s eager to join his agency. She found a flyer advertising the job, to which he grumbles that he thought he’d already taken them all down.

Despite Keiichiro’s harsh rejection, he can’t help but perv on her a little, though admirably, Mashiro shuts that down fast. She tells him off and adds that she practices Ryuku karate and can totally kick his butt if he steps out of line.

Although Keiichiro leaves her behind, Mashiro catches up and ends up joining him on the case. His extreme uncoolness quickly shines through. While tailing a target in a café, Keiichiro fumbles with the menu, tries to order whiskey, and reveals he doesn’t understand anything about modern drinks. Young and hip Mashiro orders him a vetia shot hazelnut vanilla almond caramel chocolate cream frappe with extra chocolate chips. Unfortunately, he has dentin hypersensitivity. When their target notices them, Mashiro thinks fast and pretends they’re a couple (I got the ick from this, but I’ll live). She also points out that if he wants to catch someone cheating, he needs to get with the times—people have smartphones now and are more vigilant. Keiichiro responds by asking what a smartphone even is. (Sigh.)

As they catch the target embracing her boss, Keiichiro stuns both Mashiro and readers by pulling out a large old-fashioned camera to take the shot. Mashiro quickly snatches the camera, snaps a selfie (or wefie?) with him, and successfully captures the evidence.

The next day, Keiichiro wakes up complaining about a toothache, eats a sad breakfast (just a tomato, seriously), and realizes his lighter is out of fluid. But fret not! Mashiro comes to the rescue—with a flamethrower. (One of the few moments I actually laughed out loud.) She built it just for him! To keep him safe! While there’s currently no work to protect him from, she suggests they create a website to promote the agency.

Just then, an elderly woman (who resembles a bunny, I swear) arrives asking for help finding her cat. Keiichiro hesitates, knowing how difficult animal cases are, but Mashiro has already solved it and smashes through a window to begin the chase. Midway through, she reflects that maybe she’s going about this all wrong—but she’s determined to be useful.

Enter Keiichiro, back patch and all (I like to think it’s Salonpas), who uses his detective instincts to herd the cat with a water gun and a toy before grabbing it by the scruff. Although they solve the case, Mashiro breaks down, feeling like she failed. Keiichiro carries her (and presumably the cat) back to the office, only for their client to reveal it wasn’t her cat. The feline, now dubbed Cerberus, becomes the detective agency’s official pet.

Mashiro then creates a very amateurish (but cute!) poster advertising the agency’s services. Keiichiro tears it down, insisting they need pride in their work… only for Mashiro to casually inform him she already posted 500 copies around town.

As they deal with that, Cerberus decides it’s the perfect time to chomp down on a cicada, which sends Keiichiro into full panic mode because he cannot handle bugs. That sets the stage for the next client, a woman asking them to deal with a wasp hive. Keiichiro’s bug phobia prompts him to pass the job to Mashiro, who, of course, ends up at the wrong address… in a yakuza den.

She proceeds to absolutely wreck the gokudo-gumi and somehow recruits a former yakuza named Nezu to join their agency. They assign him to the real wasp job, but—plot twist—Nezu’s afraid of bugs too! Ha!

Next chapter: Keiichiro’s laziness and messiness take center stage. A college student walks in requesting help with abusive emails targeting her club. Keiichiro and Mashiro go undercover as students to find the culprit. Keiichiro devises a cigarette code: one cig means “help,” three cigs means “can I leave.” Overwhelmed, he shoves an entire pack in his pocket, but Mashiro ignores it. After a minor scuffle with a bowling ball, Mashiro gets kicked out. She later finds Keiichiro hiding in a corner. Despite the chaos, he solves the case, and we get a hilarious Happatai reference. (Is my age showing?)

In the final chapter, Keiichiro once again laments his lack of funds. (Relatable.) Mashiro offers to help—she’s saved up 500 yen (about $3.47 USD). Keiichiro deflates. Enter Yu Asunaro, an 18-year-old prodigy and modern version of Keiichiro’s former self. He wants to become Keiichiro’s assistant to repay him for inspiring his detective dreams. But Mashiro’s not having it. They agree to a battle to determine who gets the job. Asunaro’s assistant, Kazamaki, officiates the best-of-three match. Mashiro wins (obviously), securing her position. They return to the agency to find an eviction notice taped to the door for non-payment of rent.

There are also a few bonus chapters, including one starring Cerberus the cat.

I read this manga with my high school–aged daughter, and honestly, our reactions couldn’t have been more different. She’s closer to Mashiro’s age; I’m closer to Keiichiro’s (except I do know what a smartphone is. Geez). She laughed a lot—basically cackling through the whole thing. I, on the other hand, found a few chuckle-worthy moments but mostly felt weirded out by Keiichiro’s outdated mindset and his inappropriate behavior toward a high school girl.

Look, I get that we’re all a little pervy, but there’s gotta be a line, right? Especially since Keiichiro and I are about the same age, I side-eye him hard. And honestly, 35 isn’t old. I remember when smartphones came out. I even owned the first Android! There’s no excuse for his level of cluelessness. I only really related to Keiichiro when he was suffering from insomnia, various health issues, and being broke. lol

Criticisms aside, the art is genuinely enjoyable, especially standout moments like Keiichiro’s “eagle eyes” on page 19. While some parts of the story made me uncomfortable, I didn’t hate it. In fact, I might keep reading for the comedy alone. My daughter really enjoyed it, so maybe I’m just not the target demographic for this series—and that’s okay.