Welcome to the Onsenocalypse: A Review of Hot Spring Shark Attack
Hot Spring Shark Attack (2025) is a Japanese horror-comedy that blends absurdist shark attacks, spa tourism satire, and surprisingly competent filmmaking into a cult-worthy splash. Directed by Morihito Inoue and streaming via Utopia, the film flexes rubber sharks, weird science, and oiled-up heroes with comic finesse.
Imagine Sharknado took a bath in a Japanese hot spring, met an ancient aquatic beast, and decided to stop pretending it wasn’t in on the joke. That’s Hot Spring Shark Attack in a bento box: purposefully absurd, endearingly chaotic, and shockingly competent where it matters most. Directed by Morihito Inoue in his feature debut, this horror-comedy hits all the silly tropes with finesse while inventing a few of its own.
This review spills some early and mid-movie madness (and muscled mayhem) while sparing the biggest laughs and final showdown. Proceed if you’re okay knowing a few wild plot details, but the most chaotic gems are still safe for your first watch.
A Spa Resort Built by 3D Printer and Bad Decisions
The film opens with a scene that had me cackling into my tea. A charter boat date gone wrong (or premeditated murder?) escalates into a shark attack using what might be the fakest hammerhead prop since Cocaine Shark, but it’s deployed with such intentionality, it circles back to brilliant. The young man sips from a glass of Muscat Bailey A, a common Japanese red wine, just after knocking his partner into the sea. A fin approaches. He calmly dials Water Patrol. But before you can roll your eyes, the boat is rammed, his phone is yeeted, and a woman appears, soaking wet, furious, and somehow giddy. She kicks him. Then grins.
And then? Enter a muscled man-bun who climbs aboard and flexes, and I’m in.
The spa resort at the heart of Atsumi City is a Frankenstein’s monster of bad planning. Constructed by 3D printers and marketed with Trumpian bravado (“The BEST open-air bath in Japan!”), It’s a setup for disaster. And disaster comes fast.
Also, let’s talk personal here. My son once got Croc lookalikes from a 3D printer. They broke the first day. I’m just saying, this is not what I want to hear about my rooftop shark-prone hotel. WH&S inspectors, blink twice if you need help. Enter Kohei Tanaka: long-haired police chief, would-be novelist, and unexpected softcore action hero. He’s chewing tobacco and penning kanji into bullseyes. I instantly love him. He wants to retire, maybe write manga, maybe not. Who knows? It’s that kind of movie.
Add Dr. Kose, an ecstatic marine biologist who claims with a straight face that ancient shark revivals aren’t that unusual. And the mayor? He’s more worried about influencer marketing than citizen safety.
The Science Is Trash, But the Worldbuilding Isn’t
I need to give credit where it’s due: despite the bonkers science (these “onsen sharks” have flexible bodies, travel via hot spring tunnels, and laugh while emitting electric surges), the internal logic holds. It’s dumb, yes. But it’s consistent.
Deaths are mostly bloodless, absurd, and often clever. My favorite? A spa-goer chanting, “You can’t get attacked by a shark in a bath,” before becoming shark food. The orange-bathwater attack was silly but satisfying. The cinematography plays a surprising role in elevating the camp. Foreground props cleverly obscure gore in beautifully framed shots of the coastline, or Tanaka gazing off a barrier like he’s philosophizing about sharks and spa culture.
Shark Propaganda, Muscles, Methane, and Mayhem
Midway, we get a 3D-printed submarine, a shark military strike team, and an oiled-up training montage worthy of an anime fever dream. When the sharks start disabling electromagnetic fields and laughing (yes, laughing), Tokyo gets involved. And Tanaka? Alive but glowing purple. Infected? Radioactive? Who cares. He’s glorious.
Man-bun guy appears shirtless again. He’s now the “ONSEN GUARDIAN: BATH DIVER.” I want merch.
Then comes a perfect fake jump scare, the kind that makes the one (my favorite one) in Crawl look tame. Followed by a shark spewing yellow methane gas while saying “shaaaaarrrrk.” Dr. Kose cries, because yes, the shark is crying. Allegedly.
The sharks are mostly puppets or CGI, and it doesn’t matter. The blood is orange. The deaths are implied. And I’d watch it again.
Final Verdict
You won’t find menace here. You will find creativity, love for the genre, and a dog that (unfortunately) survives. Hot Spring Shark Attack understands the assignment and sticks the dismount. If your friends don’t think you’re weird already, making them watch this might just do it.
Rating: 3.5 onsen sharks flexing mid-jump out of 5
Streaming on: Utopia VOD platforms | Theatrical release: July 11 (NY, LA, select cities)
HOT SPRING SHARK ATTACK (2025)
Director: Morihito Inoue
Premiere: 2024 Tokyo International Shark Film Festival (Audience Award)
US Theatrical & VOD Release: July 11, 2025 (select theaters; Cable VOD & Digital HD)
Cast: Takuya Fujimura, Daniel Aguilar, Shôichirô Akaboshi, Masaki Naito, Koichi Makigami, Kiyobumi Kaneko, Mio Takaki
