King Gnu’s ‘Ichizu’ Revisited: The Jujutsu Kaisen 0 Theme That Quietly Rewired the Band

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At the tail end of 2021, King Gnu dropped Ichizu alongside the theatrical release of Jujutsu Kaisen 0, and years later, it’s climbing charts again. Back then it lived and died by the anime film tag attached to it. With some distance, it reads pretty differently. Ichizu wasn’t a song that ran on adrenaline alone — it was King Gnu’s first shot fired as a vocal-driven band. Let me draw a few lines under that.

Key facts

• Digital release on December 10, 2021; the double A-side CD single Ichizu / Sakayume followed on December 29, 2021.
• Written as the theme song for the anime film Jujutsu Kaisen 0.
• Music video directed by filmmaker Taichi Kimura.
• Rebuilt as “Ichizu (ALBUM ver.)” on the fourth album THE GREATEST UNKNOWN, released November 29, 2023.
• Daiki Tsunoda has described it as “a song that’s basically all chorus” — sprint-first by design.

Take the “Jujutsu 0 theme” sticker off for a second

Talk about Ichizu only through the tie-in lens and you drop half of what it’s doing. Yes, it was written for the film that opened on December 24, 2021, and framed as a song carrying the one-track devotion between the two central characters, Yuta Okkotsu and Rika. That reading holds. It just closes the conversation too early.

What stuck in my head after the first listen wasn’t a film scene. It was the structure. That no-intro slam, the way the song shoves you into a new posture before the vocal even lands. Two seconds in, it was already outgrowing the frame of “anime movie theme.” Tsunoda himself said the song came out as something raw, sharp, and dead straight — a match for the world of Jujutsu Kaisen. Not accompaniment. A song built to swing on its own.

“All chorus” isn’t a slogan — it’s a design brief

King Gnu themselves have called it a song that’s basically all chorus. At the time, people quoted it to explain the momentum. Fair. But listening now, it reads more like a manifesto. The A-melody / B-melody / chorus scaffolding Japanese rock has been polishing for decades — the tension-and-release contract — Ichizu mostly refuses to sign it. It doesn’t build. It’s already released, and it stays released.

Reading that as pure TikTok-era adaptation feels lazy. It sounds more like a bet: can a band actually pull off three and a half minutes of only chorus, in the long-form container of a film theme, without it collapsing? The bet has quietly seeped into King Gnu songs since — the wide-screen, slow-build lineage (the Sanmon Shousetsu / Hakujitsu side) and the songs that just sprint from bar one. The first push toward running both wheels is right here.

The production, up close

Yu Seki’s drumming is one of the leads. It sounds like straight eighths pushing forward, but the placement of hits and fills is much finer-grained than it lets on. Sheet music for the drum part has circulated as the Jujutsu Kaisen 0 opening theme, and it’s still a go-to practice chart for players stepping from beginner into intermediate. Not many three-minute songs offer this many landing spots.

Tsunoda’s guitar mostly steps back and serves the vocal. What grabs the ear is how the chord progression dips into a mournful minor at specific pressure points. The “all chorus” pitch might sound like a compromise on emotional weight, but those minor drops are anything but casual. That’s what lets the devotion in the lyric theme land as fragility instead of just noise.

Kazuki Arai’s bass does something sneakier. It starts hugging the drums, then somewhere in the back half of a chorus steps forward and moves like a counter-melody. First chorus, one thing; second chorus, a little more; final stretch, more again. The reason “all chorus” doesn’t turn into repetition fatigue is that the bass is quietly doing the work.

Tsunoda’s two brains: film composer vs. band guy

Ichizu is the cleanest handshake I’ve heard between the film-scorer half of Daiki Tsunoda’s head and the band-guy half. Through millennium parade he has a whole other writing identity — orchestration, electronics, a conspiratorial relationship with visuals. In King Gnu, he prioritizes the physical mass of four people making sound in the same room.

Around Hakujitsu and Sanmon Shousetsu, the fight tilted toward the heavier, more cinematic side. Ichizu yanks the wheel the other way — a film tie-in that deliberately lets go of the score-like width and gives you three and a half minutes of four people playing in their bodies. That’s the blueprint that later leads into SPECIALZ, in my read. You don’t fill the picture’s emotional gaps with sound; you do the opposite. The band tears through at its own tempo, and the visuals catch up. What Ichizu tested, SPECIALZ turned into a template.

The other lead role: Satoru Iguchi’s voice

The King Gnu house sound is that composite tone from stacking Tsunoda’s falsetto with Iguchi’s high register. Hakujitsu is the poster child. On Ichizu, though, Iguchi’s lead is out there almost solo for long stretches. The song doesn’t color the vocal with harmony; it makes him carry it raw.

For a singer, that has to be brutal. All chorus, no hiding spots, three and a half minutes of stamina to fake nothing. Watch him do this one live and his face is a different face. That’s part of what I meant by “pivot to a vocal-driven band” — from King Gnu-as-composite-instrument to the vocalist standing alone with the weight on his back. Honest take: talk about Iguchi shifted a little after this one. From “impressively versatile” to “the guy you hand the make-or-break songs to.” And that shift showed up in live rooms before it ever showed up in chart data.

Three things to actually listen for

• The first few seconds, no build — the pre-vocal punch that resets your posture.
• The minor-key drops inside the chorus — the reason “all chorus” doesn’t turn into empty adrenaline.
• The bass movement growing toward the end — the trick that keeps the repeats from feeling like repeats.

What changed after Ichizu

From Ichizu onward, King Gnu drifts — subtly — from a band that scores your movie to a band whose vocal line carries the room. The first big wave of tie-in singles that followed — BOY, Sakayume, SPECIALZ, Shouji Mado — Ichizu was standing at the door.

The fourth album, THE GREATEST UNKNOWN, arrived on November 29, 2023. It gathered the hits released across roughly four years since CEREMONY and married them to the band’s sharper instincts. All 21 tracks are stitched into one seamless flow — the kind of album-as-single-arc statement that really only makes sense to attempt in a streaming era — with older singles re-arranged and remixed to fit the whole. Ichizu gets rebuilt as “Ichizu (ALBUM ver.),” a rounder, less jagged version. The sprint is preserved; the song is given a home in the larger narrative. When you build an album not as a hit compilation but as a current-location map, where does Ichizu belong? The ALBUM ver. is the band’s own answer.

How it hits now: a night-driving song

Right after release, I remember Ichizu being a song people put on at home to keep processing the film — a quiet-room song paired with Sakayume after the credits. A few years in, the use case has shifted.

For me, this song opens up in a car at night. Shuto Expressway, suburban bypass, whatever. You’re going the actual speed limit and your perceived speed still ticks up a notch. That “all chorus” design probably wants to be heard in motion. There’s a moment where the drum kicks line up with the way your field of view shifts, and the song steps outside its “anime film theme” costume completely. Just one read. Someone playing it on a morning commute is going to hear a different face. I’d genuinely be curious how fans use it.

Still charting: it’s the catalog, not the sprint

This song still showing up on charts isn’t just the ongoing pull of the Jujutsu Kaisen franchise. King Gnu has moved from being listened to single by single into being listened to as a whole catalog. In a playlist-first era, an up-tempo song that sprints from the top functions as a tempo balancer between mid and slow tracks. The shelf life stretches almost by accident. My read on why Ichizu is sticking around isn’t “the song has legs.” It’s that the band spent years stacking a catalog around it.

Ichizu and Sakayume, plus the MV

You can’t really talk about Ichizu without Sakayume. Same single, both A-sides, one film’s opening and one film’s ending. The designs are photo negatives of each other, and that contrast is arguably the actual subject of the release. If Sakayume lives on the build, Ichizu refuses to build at all. Coming to this backwards, I’d actually recommend Sakayume first, then Ichizu. Reverse of the film order, but going from a sunk-in ballad to being physically shaken awake by a sprint teaches you the design difference through the body.

Quick note on the video: the Ichizu MV was directed by filmmaker Taichi Kimura, whose stated goal was to fuse a polished visual world with the roughness of a rock band. Polish plus roughness — that phrase mirrors the song itself. Neatly composed, but with the mass and edge of live playing. One frame trying to hold both.

Where to go next

If Ichizu is your entry point, the natural next play is Sakayume from the same single — same film’s afterglow, opposite tempo. For a whole record, the fourth album THE GREATEST UNKNOWN (November 29, 2023) is the one. Twenty-one tracks flowing into each other, “Ichizu (ALBUM ver.)” included, designed as an on-ramp for people who found King Gnu through singles.

One question I’ll leave open

Single version of Ichizu, or ALBUM ver. — which one is the “real” version of this song to you? Purity of sprint says the single. Position on the current band map says ALBUM ver. Both are defensible, and honestly I think your answer depends on which door you walked in through. The Ichizu I heard at the end of 2021 after leaving the theater, and the Ichizu that meets me inside the 2023 album flow — same song, different song. Both are King Gnu. Both are Ichizu.