Kill Blue is a manga series by Tadatoshi Fujimaki, the mangaka who’s best known for the Kuroko’s Basketball manga series.

Kill Blue Volume One
Written by: Tadatoshi Fujimaki
Publisher: Shueisha Inc.
English Publisher: VIZ Media
Release Date: June 3, 2025

The volume opens by introducing the reader to Juzo Ogami, a hitman in his 30’s and his partner, a younger man named Kotatsu Nekota. After finishing a job, Juzo finds a can with a picture of a wasp’s nest on it but just tosses it aside.

When we see Juzo return home, it’s established that he has no idea how to deal with kids, even though he’s a divorced father. This is due to the fact that after elementary school, Juzo was already a hitman. As he starts brooding over this, Kotatsu knocks on his door because there was something he was supposed to give to Juzo. But we then see that a wasp followed Juzo home from the hit job and stings him, and Juzo collapses.

When he awakens, he finds himself in his ex-wife’s lab (she’s a scientist for the assassin syndicate that Juzo is part of) and discovers that he’s been shrunk down to a middle schooler. I have to admit that my mind immediately turned to Case Closed when I saw that plot point. But there are two major differences: Juzo is a 30-something hit man instead of a teen detective and he is shrunk down to a middle schooler rather than an elementary schooler.

It turns out the people Juzo and his partner hit were in business with a group that’s researching genetic manipulation, and that he was stung by an unusual wasp. Eri, his ex-wife begins researching the dead wasp, but she believes there’s not going to be a simple solution. In the meantime, the boss of the syndicate has a job for Juzo: infiltrate a middle school to inspect it because the boss is considering sending his daughter to the school. At first, Juzo balks, but he’s told he’ll be paid.

When we see Juzo getting ready for his first day of school, it was amusing to see that he was given a pair of glasses to be part of his disguise. That also made me think of Case Closed again how the shrunken Shinichi wears glasses as Conan Edogawa to hide the fact that he’s a younger-looking Shinichi. But, unlike Case Closed, Juzo gets to keep his real name. Juzo’s glasses also have a couple of gimmicks (communications and camera) so Kotatsu can monitor Juzo at school and provide advice.

Of course, the concept of a man in his 30’s who is unable to interact with kids being shrunk down in age and attending middle school is an interesting concept. Since he doesn’t know how to interact with the other students, Juzo quickly becomes labeled as a “weirdo,” but he doesn’t really mind. But what does surprise him is the fact that he discovers that he actually enjoys learning. Juzo never went to school beyond elementary school, so he’s learning new things and discovering how they tie in with things he’d done as a hitman. But then, he hits something in math that he doesn’t understand, since he’s forgotten some of the math basics he’d learned back in elementary school. But this leads to Juzo making his first friend, a boy in class named Ryo Shiraishi who becomes his tutor. Juzo is so impressed by Ryo that he keeps referring to him as “master.” Honestly, this was both moving and a little humorous to see. But it’s nice to see Juzo starting to go through a little bit of character development in this first volume.

But then a major revelation is made: it turns out one of Juzo’s classmates is the daughter of the president of the pharmaceutical company that’s behind the genetically engineered wasps. The plan is to try to make friends with her as a way to maybe get some intel, but she doesn’t like men, so this plan seems to be a bust. However, when Juzo stops at a ramen shop to get something to eat, he discovers that Noren (the daughter of the pharmaceutical company) works there. Juzo ends up learning about her background and why she’s working at the shop, as well as her dream of taking over her uncle’s shop one day. Noren makes Juzo promise not to say anything to the school, since she shouldn’t be working, and also makes it clear that he’s not to talk to her at school. But then, she’s kidnapped, and it’s up to Juzo to save her. This becomes at least the third incident in Volume One where Juzo’s classmates need to be saved, and he has to use clever ways to hide the fact that it’s him doing the rescuing. This instance with Noren is probably one of the amusing in the volume.

It’s time to choose which club to join, and Juzo wants to avoid the sports clubs because his abilities would make him stand out too much. When Juzo and Ryo talk about the home ec club, Juzo says something a bit sexist and happens to be overheard by Ryo’s older sister… who also happens to be the president of the home ec club. She invites him to come to their next meeting and gives him a challenge. In the end, Juzo joins the club… and we see that Noren also joins. Over the course of the volume, an uneasy friendship develops between Juzo and Noren.

But then the biggest kicker happens… Juzo is told that in order to return to his regular self, he’ll need to marry Noren because her father has announced that whoever marries her will inherit the company from him. Juzo feels this idea is simply unethical, plus there’s a lot of guys at school already trying to pursue her. The pursuit gets so bad that Noren declares to her would-be suitors that Juzo is her boyfriend. This, of course, brings unwanted attention to Juzo, but he ultimately decides to go along with it. But, we learn right at the end of the volume that hitmen are now being recruited to try to woo Noren, and the last panel seems to set the stage for the first of these hitmen to start their mission.

Kill Blue Volume One is definitely a volume that establishes the premise and the main characters of the story. By the end of it, it becomes clear that the main focus of the story moving forward will be on Juzo and Noren, and how Juzo will have to try to protect Noren from her “suitors.”

I know I made a couple of comparisons to Case Closed in this review, but there’s a major difference between these two series. Here, Juzo not only knows who is behind what shrunk him down, he already has a bit of an “in” to try to get a hold of an antidote or information about a potential antidote. Shinichi/Conan knows about the organization behind his shrinking down, but he spends time in his series trying to learn more about the organization and doesn’t have any easy way to get a permanent antidote to his condition.

When it comes to the art in Kill Blue, Fujimaki does a great job with character design. Each character has a unique look, and you can’t really confuse who’s who as you’re reading the volume. While his overall art style may look a little on the simplistic side, there are some action panels that stand out and make the reader take notice.

I thought that Kill Blue Volume One does a great job of establishing the series’ characters and concept, the writing of the story kept me engaged. While it feels like the idea of shrinking a character down in age due to something unusual created by an organization isn’t unique, I felt that Fujimaki successfully brought his own take to it. By the time I finished this volume, I found myself no longer making mental comparisons with Case Closed. What I read here interested me enough that I would be willing to read more if I come across future volumes of the series.

If you enjoy shonen manga that includes both action and comedy that are set in a school in the modern day, then you might appreciate what Kill Blue has to offer.

Kill Blue by Tadatoshi Fujimaki lives up to the humor of its premise.

A legendary hit man is turned into a 12-year-old middle schooler. He’s jaded about life, previously divorced, but adapts surprisingly well to his new circumstances, in spite of becoming the class loner.

Every time I thought “oh, I’ve seen something like this before,” the story took a direction I didn’t expect. We find out later that one of the reasons he keeps saying “I’ve never been good with kids” (not even his own) is because he missed out on school, becoming enlisted into the criminal world young. So given a chance to learn things, he surprisingly enjoys it, which I found refreshing.

The opening sequence, showing our protagonist’s life before, uses a scratchy, shadowy style that evokes the grime of the lifestyle to me. It lightens up a bit, as it should, when we move to the school setting.

I was glad that they established the premise quickly and got right into the “fish out of water” contrast. Ogami makes a friend and has to select a school club. Then there’s a mission, with a rich young lady introduced who ends up enlisting him to be her fake boyfriend to get rid of all the bullies trying to date her.

There are plenty of opportunities introduced for Ogami to use his skills, but they cleverly fit into the setting and his situation. I was surprised at how much fun reading this was.

A hit a who is a little unsatisfied with life gets bit by a bug and transformed into a middle schooler. Now he has to infiltrate middle school! This would be good for readers who enjoy The Way of the Househusband or Sakamoto Days. This one does tackle some serious topic at the same time, like bullying and divorce.

Juzo Ogami is a middle aged hitman whose body is transformed into that of a middle schooler while on the job at a pharmaceutical company. Hired to infiltrate a middle school with the children of high profile targets, he quickly become enamored with learning (he never finished elementary school in his former life) and gets more involved with student life (joining the home ec club, etc) and making friends with fellow students. Soon he learns that the daughter of the head pharmaceutical company responsible for his transformation is in his class, Noren Mitsuoka, and he ends up befriending her after discovering her moonlighting as a server at a ramen shop, while trying to get more information about reversing his condition. When the head of the company offers it to whoever marries her, he steps in as her protector (and fake boyfriend), now the target of not just the school's elites, but other young-appearing assassin transfer students.

Kill Blue, by Tadoshi Fujimaki, is a middle school battle manga currently running in Shonen Jump magazine in Japan. It joins some contemporaries (like the Shonen Jump+ titles Marriage Toxin and Dan Da Dan) in subverting the genre in some pretty fun ways. But where Marriage Toxin and Dan Da Dan go in on romance, Kill Blue rejects it; Ogami immediately rejects the possibility of dating Noren because he's still a middle aged man, and that would be creepy, no matter what he looks like. Kill Blue leans into the age-issue as a source for humor a lot; he joins the Home Ec Club when his old school sexist attitudes are brought up short, as well as Ogami's putting up with bullying to remain under cover as an "ordinary" middle schooler, he decides to stick with being Noren's bodyguard despite the obvious circumstances stacked against him at the end of this volume because "no one is as obstinate as a middle aged man," etc.

This is a lot of fun, and this first volume sets things up for the stakes to be raised as other assassins are introduced in the cliffhanger ending.

It reminds me of a cross between Spider-man and Freaky Friday. Juzo is an assassin the it bit by a wasp. Unlike in Spider-man instead of giving him superpowers it changes him back into a teenager. He must then go to school and deal with all the awkwardness that comes with being a teen. Geared towards older teens and action packed.

Top assassin turned… middle schooler? Juzo Ogami is stung by a genetically manipulated wasp during a job and regresses to the age of twelve - now he’s scoping out the school his boss’ daughter is supposed to attend and determine if it is safe. As it turns out Ogami, who never made it past elementary school, loves learning and throws himself into his new life. But can he continue to balance life as a middle schooler with his job as an assassin? And can he keep his new friends safe without them discovering the truth? Shonen fans are sure to love this (relatively) new series.