walking upstream…
YOASOBI
sourcesBillboard Japan — YOASOBI interview (Ayase on the Vocaloid-demo workflow) · Grammy.com — "It Goes to 11" (production workflow, English) · Billboard — YOASOBI on writing hard-to-sing, Vocaloid-built vocal lines · Real Sound — YOASOBI's Radwimps cover live video (tribute-album context) · Natalie — YOASOBI x "Monster Rock" TV collab (Hormone-influence corroboration)
In December 2018, Ayase, a Vocaloid producer from rural Yamaguchi, began quietly uploading songs to Niconico, Japan's do-it-yourself video platform. A year later, the story-submission site monogatary.com paired him with singer-songwriter ikura and set them an unusual brief: turn reader-submitted short stories into songs. The result, "Yoru ni Kakeru," based on the story "Thanatos no Yuwaku," went viral on TikTok in 2020 and topped the Billboard Japan Hot 100 for three weeks that June; "Idol," the 2023 Oshi no Ko anime theme, turned YOASOBI into a global streaming phenomenon. Ayase still writes and produces nearly everything alone, building every vocal line first in Hatsune Miku before ikura sings a note — "when I'm writing a song," he has said, "I don't split it into 'this is how it is for YOASOBI' vs. 'this is how it is for Vocaloid' at all." The bedroom workflow never left; it just got louder.
the sound in question
2023
IdolYOASOBI
walk the tributaries ↓
Radwimps2010s · J-rock / Alternative rock
Radwimps is the one act both members claim without qualification. Ayase, from rural Yamaguchi, told the crowd at a 2025 tribute show, "山口という田舎でもRADWIMPSが鳴り響いていたし、間違いなくRADWIMPSの音楽と一緒に育ってきたと改めて思う" — "even out in the countryside in Yamaguchi, Radwimps' music was playing everywhere; I really did grow up together with it." ikura discovered the band in ninth grade through a friend's recommendation and played their songs in a school cover band; that same night she put it more simply: "学生時代からずっとRADWIMPSさんの音楽に支えられて今日まで来ている" — "ever since school, I've been supported again and again by Radwimps' music." The duo then recorded and performed an actual Radwimps cover for the band's 20th-anniversary tribute album.
listen: upstream & heresource: Natalie — Radwimps x YOASOBI tribute-show live report (both members' testimony) ↗
2013
会心の一撃 (Kaishin no Ichigeki)Radwimps
2025
会心の一撃 (Radwimps Cover)YOASOBI
listen forPlay Radwimps' original "会心の一撃" (Kaishin no Ichigeki) against YOASOBI's 2025 cover for the tribute album Dear Jubilee, and listen for what changes. Radwimps' guitar-driven, shout-along chorus gets rebuilt in YOASOBI's own digital, synth-and-vocal-processed register — reporters at the tribute concert described the cover as arranged in "YOASOBIらしいデジタルサウンド," YOASOBI's own digital sound — while ikura keeps every one of frontman Yojiro Noda's tumbling, conversational lyric lines intact.
Neru2010s · Vocaloid / J-rock
Ayase says it started with his little sister. Home after his own band went on hiatus, he got curious what she was playing in the next room — a fan-sung cover of Neru's 2016 song "脱獄" ("Datsugoku," or "Jailbreak"). She told him the original vocal wasn't human at all: "原曲はボーカロイドが歌ってる," he recalls — "the original is sung by a Vocaloid." Ayase looked into it himself, decided "1人でできる音楽としてちょっと魅力的だなと思った" — "making music alone like that seemed kind of appealing" — and within weeks was a Vocaloid producer. That one-man workflow is the one YOASOBI still runs on.
listen: upstream & heresource: Natalie — "The VOCALOID Collection" feature #3 (Ayase on discovering Neru's "Datsugoku") ↗
2016
脱獄 (Datsugoku / "Jailbreak")Neru
2019
夜に駆ける (Yoru ni Kakeru)YOASOBI
listen forPlay Neru's "Datsugoku" against "Yoru ni Kakeru" and listen for the same trait: a vocal line built for a machine, not a throat. Ayase still writes YOASOBI's melodies the way he wrote for Vocaloid — "sometimes they're incredibly hard for a living vocalist to take breaths while singing them," he's admitted — and ikura has said much the same from the other side, naming passages where a note jumps an octave faster than she'd ever write for herself. Both tracks race a human voice through a machine's phrasing.
Maximum the Hormone2000s–10s · Metalcore / Alternative metal
Ayase traces one specific habit straight back to middle school, when, he's said, "マキシマム ザ ホルモンさんに夢中でした" — "I was obsessed with Maximum the Hormone." The metalcore band's dense, percussive Japanese lyrics apparently rewired how he hears words: "YOASOBIの歌は語感がキャッチーだと評して頂くことが多いのですが、母音やリリックに拘っているのは、マキシマム ザ ホルモンさんの影響が大きいです" — "people often praise YOASOBI's songs for their catchy word-feel, but my obsession with vowel sounds and lyrics owes a lot to Maximum the Hormone's influence." A Vocaloid producer turned J-pop songwriter, still doing a metal band's homework.
listen: upstream & heresource: Number/Bessatsu Bunshun — YOASOBI interview (Ayase on Maximum the Hormone's influence) ↗
2007
ぶっ生き返す!!Maximum the Hormone
2023
アイドル (Idol)YOASOBI
listen forCue up Maximum the Hormone's "ぶっ生き返す!!" and then the rapid-fire bridge of "アイドル" (Idol) — both pack clusters of sound-alike vowels and consonants into a small number of beats, turning lyrics into something closer to a drum pattern than a sentence. Hormone screams theirs; YOASOBI's version is glossier and faster, but the underlying trick — words chosen for how they hit the ear as much as what they mean — is the one Ayase says he picked up as a teenager.