With the highest kaiju-emergence rates in the world, Japan is no stranger to attack by deadly monsters. But kaiju don't attack every day! Sometimes, even the best and brightest kaiju-fighting heroes get a chance to relax.

Join the top troops of the Third Division of the Japan Defense Force, a military organization tasked with the neutralization of kaiju, on their days off! Kafka Hibino attempts to bare his soul in meditation, only to end up baring something else. Then, an off-duty Captain Mina Ashiro blows off steam at the arcade, Reno Ichikawa confronts his fear of ghosts, a curious cadet sets out to glimpse Vice-Captain Hoshina's eyes and uncovers a sweet surprise, and Kikoru Shinomiya finally spends time with her friends.

Kaiju No. 8: Relax has story and art by Kizuku Watanabe. English translation is done by David Evelyn with lettering and touch-up by Kyla Aiko. Published by Viz Media (December 2, 2025). Rated T.

Erica Friedman
Rating:

This manga definitely falls into official fanfic territory. Watanabe's comedic gag-comic format take on the Defense Force members in their free time is an in-universe spin-off that's goofy, harmless, and once in a while laugh-out-loud funny.

Everyone gets a moment to be made fun of here. Of course our hapless Kaiju-bodied protagonist, Kafka and his beloved kouhai, Reno, take the brunt of the jokes, since Kafka owns that clowning role throughout the original story as well. Scenarios include some time with Captain Mina Ashino at an arcade, watching scary movies and several multipart chapters are dedicated to Iharu evaluating how capable Reno is (he is very, absurdly, ridiculously, capable), and trying to get a snapshot of Vice-Captain Hoshina's eyes wide open.

The chapters looking at Kikoru Shinomiya's friendship with her dormmates Hakua and Minase were both the worst and the best. While focusing on Kikoru's tsundere personality (yay) these scenarios also included one of the funniest gags of the book when Kikoru smiles hugely and “too American” with an exaggerated art style change that is met with a “too American” smile by Hakua. I actually laughed out loud at this one gag.

The rest were a bit par for the course for gags around a ensemble cast in a manga. This is a Volume 1, so presumably we'll be getting more of this series, which gives us a chance to enjoy the banter between the principles, which will be funny and also wear on you, just as if you were listening to real dormmates making their same jokes about each other over and over.

The strength of this ensemble cast is evident, because you wouldn't really need to know much about the main story to enjoy this spin-off, but of course, it helps. So, if you're a fan of Kaiju No. 8 and like the comedy aspect of the original, here' some more goofing around to enjoy.

Kevin Cormack
Rating:

For a high-profile, successful Shonen Jump manga, Kaiju No. 8 sure seemed to end early. Complete at only sixteen volumes, I loved the whole thing from start to finish, and I can only hope that the original author, Naoya Matsumoto, returns to the world and characters he created for a sequel sometime in the future. Until then, Kaiju No. 8-starved fans like me must seek out whatever thin sustenance is offered in the shape of spin-offs. The two-volume Kaiju No. 8: B-Side is easily as good as the main series, so my hopes were high for this comedic spin-off. Sadly, my hopes were not fulfilled. While genuinely amusing here and there, Kaiju No. 8: Relax is completely disposable, missable fluff.

Reading it reminds me of my negative reaction to 86: Operation High School that I reviewed for manga guide a while back. Sometimes, more serious war stories don't translate all that well to comedy spin-offs. Granted, all the main characters are present and correct, and mostly look accurate to their appearances in the main story (though the likenesses aren't as uncannily similar as in B-side). Kaiju No. 8 always had a significant comedic side to it, but stripped of its high drama, visceral action, and pathos, that humor alone seems kind of lame.

Perhaps other readers will get more out of some of the silly skits in this volume, but other than some genuine laughs in the first story where Kikoru walks into a room where Kafka's being beaten by Reno with a baseball bat to the ass (for important story reasons, obviously), I barely cracked a smile. A later scene where Mina attempts to retrieve a plushy from a crane machine, before joining Kafka on an overly-heated arcade shooting game, is fun too, but these two scenes aren't enough for me to recommend this volume to anyone other than the most entrenched Kaiju No. 8 completionist. And I say that as someone who owns physical copies of the other Kaiju No. 8 spin-off material.

Bolts
Rating:

Kaiju No. 8 is such a fascinating franchise to me because its approach to expanding on the world is a little unique compared to other mainstream shounen that are out right now. I do enjoy Kaiju No. 8, but it's clear that the original story is very straightforward and bare bones. There's a lot of intrigue and fun moments when it comes to the main dedicated characters, but it's SO straightforward that it does mean that a lot of other side characters and potential downtime get cut out. So how does the series incorporate these elements into the story without bogging down the pacing? Well, it just makes a bunch of spin-off stories that fill in the blanks! Unlike others, which still felt like they were written in the same vein as the main series in terms of tone and execution. This feels like a true comedic spinoff that just tells a bunch of funny side stories that are happening in the middle of the main story.

When I say there's a tone shift here, I mean it. Kaiju No. 8 always has some silly elements to it, but it was ultimately pretty serious. Here, there's not an ounce of seriousness present in terms of tone; the only thing serious is how serious everybody takes the really weird situations that all of them are in, but that just adds to the comedy. Whether it's Reno trying to showcase how reliable he is or all of the girl characters besides Kikoru actually getting a bit more personality, there is a lot of fun to be had here. The story is just a bunch of really short comedic vignettes of days in the lives of the Survey Corps. My favorite story was probably the one that focused on Soshiro, who is my favorite character in the series, and how there's a running gag about him barely ever opening his eyes. Like a true spinoff, a lot of what I liked about the character is still present; they're just turned up to eleven.

The appeal of this book is going to be very narrow. This is the type of story that I think works if you're already a fan of Kaiju No. 8, and even then, if you're not looking for a specific comedic flavor of Kaiju No. 8, then this might not interest you either. It hits in a very specific pocket. Even though it accomplishes its goal extremely well with fast-paced comedic cuts, very exaggerated facial features, and a narrator who acts like they don't care what they're seeing, I think it succeeds at its hyper-specific goal. If you're looking for something in that vein, then absolutely pick this up, or at the very least check it out if you were already a dedicated fan of Kaiju No. 8, because I definitely don't see these stories working in the main series. But it is nice to imagine that this is genuinely how all of these goobers spend their time off when they're not trying to save from the next imposing threat.