Many musicians are hesitant to look back, instead focused on pushing forward. That’s not the case with Japan’s Sou, who happily learns from the past.

“I actually listen to my older recordings when I’m struggling with singing or when I want to improve my performance,” the 26-year-old artist tells scrmbl over a Zoom call in early January.

To revisit Sou’s career up until 2025 is to also see a greater shift in J-pop play out. The creator emerged onto the utaite scene in 2013, covering songs created using Vocaloid software and sharing them on Japanese video site Nico Nico Douga. He captured attention for interpretations, and soon enough was working alongside a variety of producers — including many from the online world he emerged from — to create his debut full-length album Suisou Regulus in 2015.

Not long after, the Vocaloid-centric space Sou started in became the center of Japanese pop music. In the last few years, similarly appearance-avoiding creators such as Ado and Eve — the latter being one of Sou’s close friends — have ascended to the nation’s mainstream summit, with the nervy, eclectic style Sou excels at becoming the norm. He’s become a force in his own right, both attracting a strong following while continuing to stretch his sonic palette out. Last year’s Sense Of Wonder saw further experimentation from Sou, both stylistically and in how he sings.

Underlining his status, Sou started 2025 by releasing two singles serving as themes for notable anime series. “Bakesou na Kokoro” (above) is the opening number for the second season of Yokai Gakko No Sensei Hajimemashita! while “Tada, Kimi No Mama De” — released as “Rest In peace” in English — functions as the ending for Zenshu.

“The fact that the music will be broadcast on TV as a theme song adds pressure, but I think it’s a positive force that enhances the music overall,” he says.

Sou chatted about the two new songs, the rise of Vocaloid culture globally and the benefits of revisiting the past with scrmbl. The following interview has been edited for length and clarity.

scrmbl: We’ve just entered 2025, but I wanted to start by looking back a bit, at 2024, a year that felt quite busy for you. What were some of your personal highlights of last year?

Sou: You’re right, a lot happened last year. My most memorable moment, though, was probably performing live in Shanghai and Guangzhou. It was my first time traveling abroad. While it was technically for a tour, it also felt like a half-vacation. I went to famous landmarks, and tried local delicacies.

What was the most memorable dish?

Oh what was it called again? Let me look it up quickly…it was cheung fun, I ate it in Guangzhou.

Thanks so much for looking that up! Let’s jump to 2025. You have two new songs out this month. Let’s start with “Bakesou na Kokoro.” Could you walk me through how this song came together?

Sure. “Bakesou na Kokoro” was created in collaboration with a Vocaloid producer named Chinozo. We had previously worked together on a song called “Yosasou,” which has become quite iconic among our fans. So, we used “Yosasou” as a reference point when starting the production process for this latest song.

How did you get to know Chinozo?

Before we started making music together, we used to play games, hang out, and even travel together as friends. When we first met, I thought, “He’s taller than I imagined.” We originally got to know each other online and then became friends from there.

That’s such an interesting friendship — starting online and then growing into an artistic partnership. How has your relationship changed over the years?

Not much has changed in terms of friendship, but when we’re working on music, we both switch to a more professional, “creative mode” mindset.

What games have you guys been playing recently?

[laughs] We’ve been playing a game called Valorant. It’s quite popular among my friends. Chinozo is really into it, and since I was also playing it, we started playing together.

Since we are on the topic of connections, let’s talk about the other song out this month, “Tada, Kimi No Mama De (“Rest In peace”),” which you also made in conjunction with someone. How’d that take shape?

So this song was a collaboration with another Vocaloid producer, named Sena Wataru. I had previously participated in one of Wataru’s albums six years ago, and this time, I reached out to him for this project. The offer to make “Tada, Kimi No Mama De” came from an anime project, Zenshu. I envisioned the music based on the theme and script. Wataru’s style came to mind right away, so I contacted him.

The inspiration for it didn’t come from watching the anime first, actually. Rather, I expanded my imagination from the script and design materials that I was provided. Typically, when these requests come in, the anime isn’t finished yet, so I rely on the script and concept art to form an image for the song.

That’s really interesting. Both of these songs are tied to anime projects. How does your approach to creating music change when it’s for an anime or a tie-up project compared to a Sou-only song?

Fundamentally, it doesn’t change entirely, but since the corresponding anime comes with its own themes, worldviews and atmosphere, there are simply more elements I have to consider. This adds more angles and techniques to my approach when creating a song. Also, the fact that the music will be broadcast on TV as a theme song adds pressure, but I think it’s a positive force that enhances the music overall.

Do you dislike that pressure?

Hmmmm, it’s about half and half. 

That sounds especially high pressure, creating songs for shows that will be watched not only in Japan but abroad. Do you have any mental strategies to avoid feeling overwhelmed or stressed out?

In a way, creating music in and of itself — or singing — is how I relieve that kind of pressure.

You mentioned that both of these songs were made with Vocaloid producers. How do you choose who you end up working with on the music front?

There’s no specific criteria—it’s instinct. It’s more like something just comes to mind, and I rely on that.

Oh wow, that’s good to hear! Shifting gears a bit, to look backwards — this year marks the 10th anniversary of your debut album Suisou Regulus. Do you ever listen back to it nowadays?

I actually listen to my older recordings when I’m struggling with singing or when I want to improve my performance.

It’s funny, I often ask artists this question, and many of them say how they never want to go back to listen to their older work again. They want to move forward without looking back. It’s really interesting to hear you say you revisit your work, almost as a tool to improve yourself today.

[laughs] There’s a little personal embarrassment in that, especially since something like my debut is from ten years ago. The recording environment and my skills back then were less developed, but within those imperfections, there’s a lot I had forgotten. As I’ve gained skills, my music has naturally become more polished, but when I listen to my older singing, even though it’s unrefined or immature, there’s a certain charm to it. It reminds me of things I’ve forgotten now, so I listen to it quite often.

That’s a very positive way to view it. This might be a tough question, but can you give a specific example of something you realized recently while listening to your older music?

Hmmm, it’s not so much about a specific part of one song, but for example, in the song “Sakasa Syndrome” from my first album, my vocal range at the time was narrower than it is now. There’s this feeling of desperately singing at the edge of my range — pushing through, even though the notes aren’t perfectly hit. That rawness moves me when I listen to it now.

That’s incredible. If you could go back and talk to yourself in 2015, when your debut album was released, what would you say?

I wouldn’t want to say anything that might change the future, like telling myself what’s ahead [laughs]. But I would want to give myself advice about things I was struggling with back then, like singing, mixing, and production techniques. I’d probably teach myself about desktop music tools and plugins. [laughs]

Are there any specific plugins you’d recommend to your past self?

Hmm, which plugin would I recommend? I’d tell myself to start using Ozone sooner. [laughs]

You came from a background in utaite culture, which is closely tied to Vocaloid. You’ve worked with many Vocaloid producers, and utaite is an important part of your identity. In your opinion, how have Vocaloid and utaite culture changed over the past ten years?

Over the past decade, the internet has rapidly expanded, and with it, Vocaloid and utaite culture have become more widespread. I feel like they’ve been increasingly accepted by society, making it easier to be active in the scene. The number of people involved has grown, the genres of Vocaloid songs have diversified, and as an utaite, I think it’s become something you can proudly say you’re a part of.

That’s fascinating. Something I’ve noticed recently is how much bigger Vocaloid and utaite culture has become outside of Japan. In the past two years, I’ve seen a significant increase in interest from people overseas, including for your music and the entire world it came from. Why do you think, as someone so close to this world, it has become so appealing to so many people?

I think YouTube has had a huge impact. Since I started uploading on YouTube, I’ve received a lot of support from overseas fans, and it feels like my work is reaching a global audience.

Another reason for its widespread appeal is that Vocaloid isn’t just about music — it extends to cosplay, illustrations, fan creations, and various other areas. This allows people to participate in the community in many different ways.

In the past one or two years, has there been anything in music — specific songs, artists, or trends — that has really excited or inspired you?

Let’s see. One thing that really struck me is Project Sekai, the mobile rhythm game. It’s amazing to see Vocaloid music finally become part of a rhythm game. Many people who didn’t know about Vocaloid music before have been introduced to it through Project Sekai. I feel like it marked a new level of growth for the culture.

Another thing related to Vocaloid and utaite culture that I’d like to ask is about how many creators in this space, including yourself, tend to keep their appearance and private details hidden. Why do you think this is common, and why have you personally chosen to do the same?

At first, it was just the norm for people on the internet to not show their faces. Personally, I don’t have much confidence in myself. I was just an otaku singing as a hobby in the corner of my room, so I didn’t feel the need to show my face. I’m already very satisfied with having so many people listen to my music, so I’ve never felt the urge to reveal myself. Also, since we don’t meet people in person on the internet, I think it’s fun for listeners to imagine what kind of person I am based on my voice, or the character they associate with me.

That makes sense. It seems like letting the audience imagine is part of the fun.

Yes, I think it’s enjoyable for both me and the audience.

When I talk to other utaite creators, they often express the same idea — that they’re just happy their music reaches people and feel no need to reveal their identity. It seems like this mindset is deeply ingrained in the culture.

Yes, I think so. When Nico Nico Douga first started, people weren’t as open as they are now on platforms like YouTube. Back then, people used illustrations or animations instead of showing their faces.

I didn’t show my face at all, so I didn’t have to worry about hiding it. But as fan interactions grew, people started making travel videos and other content, which became popular. At that point, creators began using illustrations, mosaics, or other techniques to avoid showing their faces.

Totally different question — what’s a typical day in the life of Sou like? 

Normally, I either record music, play games, watch movies or anime, or read manga.

What’s the most important lesson you’ve learned in your career as an artist?

The biggest lesson I’ve learned is to trust in the feeling of “loving what I do.” That feeling has grown stronger every year, and staying true to it has allowed me to keep going. Even when I felt like giving up, the thought of “I want to do this because I love it” kept me going. It’s important not to forget that feeling.

Last, what are your goals for 2025?

My goal for 2025 is to try arranging music by myself. I already work with DTM and do mixing, so while I’m not sure if I’ll be able to do it within this year, it’s something I’d like to aim for.