Kenshi Yonezu’s Music Sets the Emotional Core of ‘CHAINSAW MAN – THE MOVIE: REZE ARC’

Hypebeast spoke with the acclaimed singer-songwriter on how he captured the serie’s dualistic nature with “IRIS OUT” and “JANE DOE.”

The excitement for the CHAINSAW MAN – THE MOVIE: REZE ARC film is palpable as it heads toward its US premiere this week. The movie’s musical foundation rests on two new theme songs produced by Kenshi Yonezu: “IRIS OUT” and “JANE DOE,” with the latter being Yonezu’s first collaboration with Hikaru Utada, cementing a historic moment where two of Japan’s most influential singer-songwriters of the modern generation creatively collide.

Yonezu is no stranger to the franchise; his previous track for the CHAINSAW MAN anime, “KICK BACK,” was a global smash and achieved the first-ever RIAA Platinum certification for a Japanese-language song. For the film, he consciously anchored the new music in the manga’s thematic duality. He noted that the brilliance of the series lies in its rare ability to weave extreme violence with comedy — a blend he sought to mirror in the score. To achieve this, he gave the two theme songs almost entirely different sounds and moods, yet both tracks address a core theme central to the film.

The opening song, “IRIS OUT,” has already made history, rocketing to the Top 5 of the Billboard Global 200 chart at the start of the month, marking the highest-ever charting position for a Japanese-language song. This track is a jam-packed ensemble: a pounding bassline evokes Denji’s thumping heart rate; glitchy techno accents hint at his unruly thoughts and a ragtime-esque arrangement brings forth the chaotic world and whirlwind of events he’s experiencing.

This manic energy contrasts with “JANE DOE,” the closing duet with Utada that offers a more restrained yet equally stirring emotional landscape, perfectly encapsulating Denji and Reze’s love story. Its eerie, ethereal string arrangements hint at Reze’s hidden motives and identity, while a tender piano waltz underscores the childlike purity of longing for love and companionship.

Your music has a unique way of capturing a story’s emotional core. What specific themes from CHAINSAW MAN resonated with you most deeply? And how did it influence your compositions?

CHAINSAW MAN contains a great deal of violence; this series artfully expresses how that very violence can be comical. You’re swept up and spun around in a seamless succession of violence and laughter. I don’t know any other manga in the shonen genre that weaves violence and laughter together with such brilliance.

CHAINSAW MAN is known for its blend of extreme violence and profound emotional moments. How did you balance those two opposing forces in the two theme songs you wrote for the new film?

My first goal was to give “IRIS OUT” and “JANE DOE” completely different tones. Both songs embody misunderstandings that arise when people cannot fully connect, especially when the interaction is between couples. I think it’s a theme that’s closely related to the duality shown in CHAINSAW MAN. I felt it was important to incorporate that kind of duality in a manga series like CHAINSAW MAN – a piece of media that is both comical yet serious, violent yet melancholic.

If you had to choose a single word to describe the feeling for each of the songs you created for CHAINSAW MAN (both the TV anime and the film), what would they be?

Since it’s hard to express emotions with a single word, I simply described each song in one. “KICK BACK”- Poverty; “IRIS OUT”- Lust; “JANE DOE” – Traces. I think that about sums it up.

Without giving away any spoilers, was there a specific scene or a character’s journey in the film that you found particularly inspiring for the new songs?

There’s a scene in the film where the two sneak into a school at night. That was a pivotal scene that helped shape the song. The scene has an incredibly melancholic touch and it’s one of my favorite sequences of the REZE ARC. From there, I focused on meticulously following Denji’s gaze and coming to love Reze.

Your collaboration with Hikaru Utada is a major moment for fans. How did this partnership come about?

At first, I thought it probably shouldn’t be me singing. My male voice didn’t feel at all appropriate for the ending of the REZE ARC movie. I had a strong sense from the start that the song needed to be led by a female voice to work properly. I really like the duet “I’ve Seen It All” by Björk and Thom Yorke from Dancer in the Dark. I felt that kind of nuance would fit perfectly, and started creating the song with that in mind.

From there, there were various twists and turns — I even tried a version that was nostalgic and evoked youthful feelings — but it felt overly circuitous. In the end, I felt that a male-female duet with a slightly melancholic, dark vibe would be the most fitting. That’s how it came together.

What was the very first conversation you had with Hikaru Utada about the song?

I explained to Utada that I wanted to create a duet between “a girl carrying something incredibly complex and a boy who essentially doesn’t understand that at all” and asked them to sing it in that way. They approached that with their own take and that’s how it took shape. Other than that, I didn’t offer any detailed directions as I felt it was best to let Utada follow their own instincts.

Both of your musical styles are incredibly distinct yet carry a deep emotional weight. How did you navigate the creative middle ground for both of your voices and artistic approaches?

Since Utada lives in London, the recording process was carried out by exchanging data, almost like corresponding back and forth in letters. We did have one phone call. During that conversation, they told me something along the lines of, “I think if you sing it this way, your voice will stand out more” – I really felt they were right and that’s because Utada and I have very different sensibilities when it comes to singing.

Utada is a musician rooted in R&B and other styles that move with a laidback, rich sense of rhythm. On the other hand, I come from a background in Vocaloid and computer-generated music, where I tend to place more importance on the vertical grid lines. At times, I also lean towards alternative rock-type sounds with a sense of “urgency.” Since we’re so different in nature, when Utada’s voice is layered onto something I’ve written, it makes the song feel much more full-bodied. That difference between us was really wonderful.

As I mentioned earlier, the song ended up embodying the contrast between a girl carrying something deeply complicated and a boy who, at heart, doesn’t understand any of it. That wasn’t something we set out to do at all — it just happened as a result. But it feels like we arrived at the one and only way it could be.

If your entire discography were a journey, where does this new music for CHAINSAW MAN fit in? Is it a new chapter, a side quest, or something else entirely?

One of my goals for songwriting this year was to create music with the pure, childlike enthusiasm I had as a child. Having created music for so many years, I seemed to have forgotten why I make music in the first place – I felt compelled to return to where it all began. I thought back to my childhood, where I sat in front of the computer, programming, recording music on my own and tried to recapture that feeling as much as possible.

If you were a Devil in the CHAINSAW MAN universe, which one would you be?

I’d be a Bamboo-shoot Devil, growing steadily, then smashing through the floorboards of people’s homes.

If you could give Denji one piece of life advice, what would it be?

Stay healthy.

Beyond the film, if your music for CHAINSAW MAN could be paired with any food, what would it be and why?

A heavy, greasy, flavor-packed burger and a can of Coke.