Yunagi (夕凪機) and Kaf (花譜) have released a joint cover of YOASOBI’s Biri-Biri (ビリビリ), and it’s a pairing worth pausing on: one half of this duet is one of KAMITSUBAKI STUDIO’s most established names, the other is a newer voice from a project that grew up alongside it. Putting them on the same track together says a lot about how much faith is being placed in where this newer act is headed.

Who’s Actually Singing This

Yunagi is a member of Tsumitobatsu (罪十罰), a three-person virtual singer unit built around aggressive, vocally demanding tracks, alongside members Hinageshi (氷夏至) and Mikoto (美古途). Tsumitobatsu is one of two units under Shoujo Kakumei Keikaku (少女革命計画), a music-and-story label born from a partnership between KAMITSUBAKI STUDIO and Shinka (深化), the company founded by KAMITSUBAKI’s own producer PIEDPIPER, with the project officially debuting its artists in August 2024. Kaf, on the other hand, needs no introduction to anyone following KAMITSUBAKI — she was the label’s first virtual singer to headline Nippon Budokan and remains one of its defining voices. Having her share a mic with Yunagi here reads as a pretty clear co-sign.

The Song They Picked

Biri-Biri is a YOASOBI track written and produced by Ayase, originally released in November 2023 to mark the one-year anniversary of Pokémon Scarlet and Violet, built around a commemorative short story by Ayano Takedo. It’s an electropop song with a title that’s straight onomatopoeia — the Japanese sound for a jolt of electricity — and it charted inside the top 20 on both Oricon and Billboard Japan Hot 100 on release. It’s a high-energy, hook-driven pick, and one that gives two strong vocalists plenty of room to trade off and layer against each other.

How the Two Voices Work Together

Pairing Kaf’s more ethereal, distinct tone against Yunagi’s grounding in the harder-edged style Tsumitobatsu is known for gives this cover a different texture than either artist typically works in solo. It’s the kind of vocal contrast that a cover like this is built to highlight — two very different instruments finding a way to complement rather than compete with each other over the course of one song.

Part of a Bigger Introduction

For Yunagi and the rest of Shoujo Kakumei Keikaku, getting a track like this next to Kaf’s name is a meaningful moment — it puts a still-developing project directly in front of an audience that already trusts KAMITSUBAKI’s flagship talent. If the goal is to get more listeners paying attention to Tsumitobatsu and Shinseiki (心世紀), this is exactly the kind of pairing that does it.

Track Credits

• Title: Biri-Biri (ビリビリ)
• Vocals: Yunagi (夕凪機), Kaf (花譜)
• Original Song By: YOASOBI
• Original Lyrics & Music: Ayase
• Instrumental: YOASOBI
• Illustration: PORO
• Movie: Kokoa Panda (ここあぱんだ)
• Mix: Tomiaki Ishikawa (石川富章)

▶ Watch: Yunagi × Kaf — Biri-Biri (Cover) on YouTube