Aimer is teaming up with the blockbuster anime Demon Slayer: Kimetsu no Yaiba once again. The “Zankyosanka” songstress was tapped to perform one of the two theme songs gracing the first of the anime trilogy Demon Slayer: Kimetsu no Yaiba – The Movie: Infinity Castle — Part 1: Akaza Returns alongside LiSA, with Aimer singing “Taiyo ga Noboranai Sekai” (English title: “A World Where the Sun Never Rises”).
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The songwriting team for the track includes Hikaru Kondo, the film’s general director, and Go Shiina, the composer of the soundtrack, both from the production team of the title’s anime series. Aimer’s vocals resonate with the story of the Infinity Castle movie, filling the song with strength, determination, and vulnerability. How did the “Asa ga kuru” vocalist approach this new song born from the movie? In this latest interview, the 35-year-old singer reflects on her connection with the Kimetsu series and opens up about the creative process and essence of her latest collaboration.
You first collaborated with the Demon Slayer: Kimetsu no Yaiba anime through “Zankyosanka” and “Asa ga kuru,” the opening and ending theme songs for the Entertainment District story arc. You’d already worked on many tie-ins for other works. What was it like working on the Kimetsu series?
When I was first tapped to do it, the work was already well known and LiSA had performed all of the theme songs up to that point, so there was some pressure. Still, I was able to work on “Zankyosanka” with the same team I’d been working with since my debut, and I’d also worked with Yuki Kajiura, who wrote “Asa ga kuru,” and ufotable, the production company behind the Kimetsu anime, so I was confident that we could create something great. Being able to join the Kimetsu anime team was a huge honor.
“Zankyosanka” went on to rule Billboard Japan’s 2022 year-end Japan Hot 100, and you performed it for your first appearance on the prestigious Kohaku Uta Gassen year-end music extravaganza. What does this song mean to you?
It’s a song that changed my concerts. In the early days of my career, there were a lot of ballads in my repertoire and the audience was mainly seated at my shows. I focused on making songs that reflected my inner world. But as I gained more experience, I began to realize how important performing live is, and last year I went on an overseas tour.
The Aimer 3 Nuits Tour 2024 that made stops in Shanghai, Taipei, and Hong Kong, your first tour outside of Japan in about five years.
The local crowd sang along with almost all the songs. In particular, “Zankyosanka” has a scat-like part that everyone can sing along to, so they sang it together with great enthusiasm. Inspired by their energy, I thought maybe my audience in Japan would sing along too, so I decided to make the next domestic tour (Aimer Hall Tour 2024-25 “lune blanche”) one where I build together with my audience. “Zankyosanka” was a big turning point for me.
How did you feel when you were asked to collaborate with the Kimetsu franchise again, to sing “A World Where the Sun Never Rises” for the latest movie version?
When I first heard about it, I was taken completely by surprise — I felt more surprised than happy, to be honest. Various artists have performed theme songs for the Kimetsu anime series since the Entertainment District arc, and until now, I hadn’t had many opportunities to sing the theme song for the same work after some time had passed. And the fact that it was one of two theme songs with the other by LiSA was also a huge surprise, so I felt both honored and delighted.
“A World Where the Sun Never Rises” was written by the three people involved in the creation of the movie. Hikaru Kondo, the movie’s general director, wrote the lyrics and the composition and arrangement were handled by the composers of the film’s soundtrack — the former by Go Shiina, the latter by Shiina and Sachiko Miyano. It’s a song made specifically for this movie.
They’re all probably constantly thinking about the Kimetsu anime, and I couldn’t imagine what people like that would come up with as a theme song. When I first heard the demo, I thought it was difficult and was like, “How should I sing this?” to be honest. There were parts that sounded like opera, the synths sounded like techno, and there were elements of rock as well. I thought it was a really interesting song, but also wondered what the correct way to sing it would be.
As you say, it feels like the true power of this song can’t be drawn out by simply following the melody. It’s like your vocals are so integrated with the music that the song is only complete with it.
When requesting a composer to write a song for me, I let them know my vocal range in advance. Most composers will then create melodies within that range with some leeway, but Mr. Shiina used the entire range, pushing it to the absolute limit. After I recorded it, he said, “I really love your low notes, so I wanted to include them, and I also wanted to make sure your high falsetto could be heard, too, which is why I composed the melody like that.” The chorus is my highest key, so I couldn’t sing it in my natural voice and had to use falsetto, and the first verse (A-melo) is at my lowest register. I rarely use long vibrato or falsetto with a classical-tinged, intense sound, so I realized that the song turned out so awesome because he intentionally aimed to “fully utilize Aimer’s voice.” Since the song is crafted to highlight my voice, it’s easier to add dynamics.
I see. Because this song makes full use of your limits, once it settles into your body, you’re able to effectively showcase your vocals.
I think Mr. Shiina took my vocal range into consideration and carefully adjusted every detail to make this song fit into the movie. When I sing long notes, I tend to leave just a little bit of breath at the end, and I was happy when he clearly left that part in the mix so it could be heard at close range. It reminded me of how much attention he pays to even the smallest details.
I see now that “A World Where the Sun Never Rises” became a song that enriches the Infinity Castle movie because it’s the result of everyone’s relentless pursuit of perfection.
They spoke about “the emotions of the Demon Slayer Corps and the situation as the decisive battle begins” and about wanting to “give meaning to the inclusion of the theme song (at that particular moment in the film).” I think the Infinity Castle Arc conveys the core values of Demon Slayer: Kimetsu no Yaiba in a straightforward, pronounced way, so I wanted to express those values through the song as well. Mr. Kondo and Mr. Shiina were present at the recording, and I recorded the vocals while watching special footage from the movie.
Is there a notable difference between singing your own lyrics and singing someone else’s?
When the lyrics are written by someone else, it feels like I can interpret the words intuitively, allowing me to focus on expressing the song according to the sound, and the resonance of the words. When I write my own lyrics, I understand the intention behind each word, for better or worse, and sometimes my ego gets in the way. I felt like I became part of the movie through “A World Where the Sun Never Rises,” which was a refreshing experience. It was my first time singing a song that has a perspective like that, so it was very interesting and exciting for me.
From what you said, “A World Where the Sun Never Rises” feels like it’s a song with a strong sense of “putting up a fight.” Personally, would you say that you live with a fighting spirit?
I do want to be calm, but I’m the type of person with intense emotional ups and downs, so I’d say yes. That’s why I’m constantly moved by the depth of each character’s story in Kimetsu no Yaiba. The story features powerful demons, and even the demons have motivations to become stronger. In Kimetsu, anger and sadness over what has been taken away or lost, and the strong desire to protect what’s dear to you, drive the battles. I also feel that I need to be strong to protect what’s dear to me in my daily life.
Maybe it’s the love for the things we hold dear that makes us stronger.
Right. In the Infinity Castle Arc, each character has something they absolutely can’t give up, and I think the underlying emotion is “love” in their desire not to let their friends or descendants experience the same sadness they’ve gone through. It’s a strong emotion so it can sometimes become distorted, but everyone is fighting based on their beliefs. I think “A World Where the Sun Never Rises” captures the excitement of the beginning of the Infinity Castle Arc and when you listen to the full version, you’ll understand the reason behind the title and the dynamics created by the varying intensities of emotions.
You seem to have consistently focused on the compatibility between sound and your vocals since your debut. Where does that originate from?
I’ve always loved songs where the vocals blend right in with the sound and exist in the music without sounding unnatural. The reason I started singing was because I wanted to be able to produce those kinds of songs and vocals. It might sound presumptuous to say that I want to use my voice as an instrument, but I’ve always wanted to express such things through song.
I think your songs resonate with listeners from outside Japan as well because they can intuitively get what you’re singing about even without following the lyrics.
I’m glad to hear that. I always hope that the thoughts behind the song and my own emotions can be conveyed through the sound and tone, even if there’s a language barrier. During my overseas tours, seeing everyone getting so excited in large venues made me realize that each song from the animation projects I was involved in was reaching people in faraway places, and it was very moving. It also reminded me how music transcends cultural and language differences. When I sing live, those emotions just naturally well up and turn into song. That’s why I love performing live and I want to proactively do live shows all over the world.
“A World Where the Sun Never Rises” will probably become another song of yours that resonates with people everywhere.
We were able to capture the best takes because everyone involved was present at the recording. The sound and my voice blended together better than I could have imagined, so I feel confident about it, and I’d like to draw from this experience in the future.
The idea of having to be strong to protect what you hold dear that comes across from Demon Slayer: Kimetsu no Yaiba is both personal and universal. I should also value this idea if I’m to continue doing music, and this sentiment grows bigger and stronger every day. Next year (2026) marks the 15th anniversary since my debut, and I hope to express these feelings through my music at that time.
Perhaps the reason why you’ve become stronger is because you have more things you want to protect.
I’m not a strong person, but the reason why I’ve been able to come this far is because of my fans who listen to my music. 15 years from now, 20 years from now, I’ll probably keep making music with a desire to become stronger so I can protect the people or things that are important to me. I want to give back to my fans through my music, like, “It’s thanks to you that I’ve been able to come this far.” I want to stay true to myself and keep singing.
This interview by Sayako Oki first appeared on Billboard Japan
