How to Sing Like Shimizu (back number): Vocal Range, Vibrato-less Long Tones & the Technique Behind It

Singing like Shimizu Iyori of back number isn't about matching a wide vocal range — it's about sustaining a vibrato-free straight tone all the way through a phrase and concealing the shift from chest voice into falsetto so it never sounds like a break. That's exactly what makes the fade-out endings in "水平線" and the sudden jumps in "高嶺の花子さん" demanding, and both are trainable through focused technique work regardless of your natural range.

English-language covers of his songs exist, but detailed English vocal breakdowns are rare — this guide is meant to fill that gap.

Safety note: None of the techniques here should cause throat soreness, a pressed or squeezed feeling, or hoarseness lasting beyond 24 hours. Straight tone and register transitions come from breath support and vocal fold coordination, not from pressing the throat. If a phrase starts to feel effortful rather than controlled, drop the key or reduce intensity. Consult an ENT specialist for hoarseness lasting more than two weeks.

Shimizu's Vocal Profile

Shimizu Iyori (清水依与吏) is the vocalist and guitarist of the three-piece band back number — and outside Japan, he may be best known as the composer of BTS's 2021 Japanese single "Film Out," which makes his catalog a natural entry point for listeners arriving from K-pop fandom into J-pop vocal technique. Within the band itself, the bass plays a purely backing role, so the lead melody lines in back number's catalog are effectively all sung by Shimizu — a rare case where there's no "is this note actually another member's part" ambiguity that comes up with most band vocal analyses.

There is no official voice type classification. Japanese vocal-coaching sources describe his voice as "soft but with a core in the mid-high register, never turning sharp or harsh on high notes." Song-level data puts his documented chest voice floor at F#2 and his chest ceiling around C5, and some sources infer a light or lyric tenor from that ceiling — but that remains an inference, not a confirmed classification.

Song-level range data and physiological range data are two different things and need to stay separate:

• Song-specific figures (from a catalog-wide vocal range database): D3 to G4 with falsetto to C5 in "水平線", B2 to A4 with falsetto to C#5 in "クリスマスソング", A2 to A#4 with falsetto to C5 in "花束", F3 to G#4 with falsetto to C5 in "瞬き", D3 to B4 in "ヒロイン", and E3 to B4 with falsetto to D5 in "高嶺の花子さん". Pulled across his whole catalog, the extremes run from chest F#2 to C5 with falsetto reaching E5 — but that's the widest low and widest high pulled from different songs, not a range used within any single one.
• Physiological range: there is no publicly documented measurement. Translating the catalog-wide extremes above into "Shimizu sings F#2 to E5" would be a category error — no single song asks for that full span.

His vocal identity comes down to two defining traits:

• A vibrato-free straight tone — instead of closing out a ballad phrase with vibrato, he eases off subglottal pressure gradually so the note fades out naturally.
• Tone blending that hides the chest-to-falsetto shift — keeping the larynx position fixed through the transition so the tone color of both registers matches as closely as possible.

Shimizu's Signature Songs — by Vocal Challenge

Working through his catalog by technical demand gives you a natural training order. Transpose any of these to a key that fits your voice.

Start at the top and move down only once each technique becomes reliable. "高嶺の花子さん" is the destination, not the starting line — it demands a chest A4 in the verse, a chest B4 in the chorus, and a falsetto D5, with abrupt jumps between them, and it's easy to strain without the groundwork from the songs above it.

The 3 Techniques Behind Shimizu's Sound

Vibrato-Free Straight Tone With a Fading Phrase Ending

Shimizu's ballads don't close out phrases with vibrato. In a slow song like "水平線", that's actually harder, not easier — with no vibrato to help mask pitch drift, you have to maintain precise vocal fold closure while gradually easing off subglottal pressure so the sound evaporates rather than stops. The common mistake is simply releasing breath or cutting the sound abruptly at the end. In Bloom Vocal, Straight Tone to Vibrato (D-5) and Messa di Voce (F-1) exercises train this volume decay control. The mix voice practice guide covers the register-blending fundamentals behind this kind of tone control.

Concealing the G#4/A4 Chest-to-Falsetto Shift

The chorus of "クリスマスソング" sits repeatedly around F#4/G#4, with the shift from chest voice into falsetto happening within a single phrase. Shimizu uses a mix bridge that keeps his larynx position fixed, matching the tone color of chest voice and falsetto so the passaggio never becomes audible. The common mistake is pushing harder or letting the larynx rise right before the shift, which makes the tone brighten abruptly. Bloom Vocal's Chest-to-Mix Transition (C-4) and Passaggio Vowel Modification (C-13) exercises train this concealed transition.

High Notes Without Pressing

On ascending notes like the A#4 in "花束" or the B4 in "高嶺の花子さん", Shimizu doesn't add twang or vocal-tract compression to push the sound out. Instead, he keeps the pharynx open and supports pitch through vocal fold closure and breath support alone. Pushing harder from the throat to sound bigger or higher is the most common mistake and the fastest way to strain. Bloom Vocal's Mixed Resonance Blending (E-11) and Vowel Narrowing (C-5) exercises train this open, unpressed high-range delivery.

How to Train Toward Shimizu's Style

Step 1 — Confirm your comfortable range and starting song

Run a range test to find your comfortable middle voice, then start with "瞬き" (F3 to G#4), the narrowest-range song in his catalog. A stable middle register matters more than reaching for a wide range on day one.

Step 2 — Practice ending phrases with a vibrato-free straight tone

Sing the phrase endings in "水平線" without letting vibrato take over — ease off subglottal pressure gradually so the note fades out naturally. Slow down immediately if pitch starts to wobble, and try again.

Step 3 — Train the concealed chest-to-falsetto transition

In the F#4 to G#4 chorus of "クリスマスソング", keep your larynx position fixed while practicing a mix bridge that matches chest voice and falsetto tone color. Record yourself to check whether the tone color breaks at the transition point.

Step 4 — Build high notes with an open pharynx instead of pushing

On notes like the A#4 in "花束" or the B4 in "高嶺の花子さん", practice keeping the pharynx open without adding twang, supporting pitch through vocal fold closure and breath support alone.

Step 5 — Run an AI feedback loop on a single phrase

Choose one 4-to-8 bar phrase — ideally one with a straight-tone ending or a chest-to-falsetto transition — record it, and use Bloom Vocal's AI coaching to score your pitch accuracy, register transitions, and breath support. The AI surfaces habits like lost breath support at a phrase ending or an audible break at the transition point that are difficult to catch by self-listening alone.

Check Your Cover with AI

Ear-based imitation has a ceiling: you can't reliably hear your own phrase ending cutting off abruptly, a chest-to-falsetto break becoming audible, or your throat tensing on a high note while you're performing it. Record a passage from Shimizu's repertoire — the fading endings in "水平線" or the abrupt jumps in "高嶺の花子さん" — and Bloom Vocal's AI scores your pitch accuracy, breath support, register transitions, rhythm, and expression on a 1–5 rubric, then recommends the specific exercises to address your weakest area first. It turns "that felt strained" into "your phrase ending lost breath support — drill the straight tone to vibrato and messa di voce exercises."

For more on how to sing like other J-pop vocalists, see Fujii Kaze, Kenshi Yonezu, Aimyon, and Yuuri.

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References

• Sadolin, C. (2000). Complete Vocal Technique. Shout Publishing. [Vibrato on/off control and mix-bridge strategies for matching tone color across a register transition.]
• Titze, I. R., & Verdolini Abbott, K. (2012). Vocology: The Science and Practice of Voice Habilitation. National Center for Voice and Speech. [Subglottal pressure control and vocal fold closure as the basis for sustained straight tone and stable high-range singing.]