Overview
KAFU (可不, Kafu) is the flagship vocal synthesis library of KAMITSUBAKI STUDIO’s “Musical Isotope” project, powered by CeVIO AI and Synthesizer V, with voice provider KAF.
Released on July 7, 2021, KAFU became a phenomenon in VOCALOID producer culture, featuring in viral hits like Tsumiki’s Phony.
VOICE PROVIDER
KAF
SINGING ENGINES
CeVIO AI; later expanded to Synthesizer V AI
CHARACTER DESIGN
PALOW.
RELEASE
7 July 2021
Design and voice identity
PALOW.’s character design uses white and yellow, circular pupils, a hooded outer layer, and geometric details. It makes KAFU legible beside KAF while establishing a separate voice-character identity for creators.
Timeline
| Period | Milestone | Notes |
|---|---|---|
| October 2020 | Voice survey | Three prototype singing types were presented; Type B became the basis of the released library. |
| November–December 2020 | Early covers | Hinadori, Shinzō to Karakuri, and Kako o Kurau were published as early demonstrations. |
| May–July 2021 | Commission series and release | A broad producer lineup introduced the library; the final release arrived on 7 July. |
| Later | Engine expansion | The product line grew beyond its CeVIO AI launch with a Synthesizer V AI edition. |
Commissioned-song index
Show the launch-era song index
| Date | Song | Creator |
|---|---|---|
| 2021-01-09 | Hologram | Hifumi |
| 2021-02-20 | Cute na Kanojo | syudou |
| 2021-03-07 | Ice Cream | Guiano |
| 2021-04-10 | Retropolis | R Sound Design |
| 2021-05-01 | Hana to Nare | Yunosuke |
| 2021-05-08 | Suimenka | Osanuma Paseri |
| 2021-06-05 | Phony | Tsumiki |
| 2021-07-17 | Cat Loving | Moimi Kashii |
These official commissions are an entry point rather than a closed discography: KAFU’s significance lies in the expanding body of songs made by independent creators. Phony, Marshall Maximizer, and Cute na Kanojo are widely cited examples of this ecosystem.
Project connections
KAFU opened the Musical Isotope project. The subsequent SEKAI, RIME, COKO, and HARU voice characters extend the same creator-facing framework.