A crowdfunding campaign was launched on May 28, 2020 to fund for Koharu Rikka's VOICEROID2 voicebank and its stretch goals, which included the final stretch goal for 25 million yen: a singing voicebank. This amount was reached on June 6, about a week and a half after the campaign began, but the actual synthesizer was not specified at the time. On June 26, Synthesizer V Studio was revealed as her singing engine. On August 8, it was announced that recording for her Synthesizer V bank started.
On October 30, Rikka was announced that she would be developed for the CeVIO AI voice synthesis engine for speech. For singing, she was confirmed to have not only a Standard voice database but also the newly introduced AI type of voice database. She was slated for a Spring 2021 release.. In a press release from TOKYO6 ENTERTAINMENT, it was announced that the reason why Rikka was in production for CeVIO AI was due to the fact that it also used AI technology, unlike VOICEROID.
On February 18, 2021, during an AH-Software Co. Ltd. Livestream, Rikka's Synthesizer V AI voice database was showcased. Following the stream, AH-Software announced a special campaign on Twitter allowing users to apply via DM to receive a physical copy of Synthesizer V Studio Pro and Synthesizer V Koharu Rikka AI Complete.
Rikka officially released on March 18 for both CeVIO AI and Synthesizer V Studio. Lite versions of the Synthesizer V voice databases were also released on the same day via AH-Software's website.
On March 24, 2022, Rikka was confirmed to be receiving a physical box for only her AI voice database on April 13. This was due to high demand for AI-type voices. On March 26, the release of Synthesizer V Studio version 1.6.0 brought new features: Vocal Mode and Instant Mode. TOKYO6 announced that these features would be brought to Rikka and Natsuki Karin later due to the need of making adjustments to the voice databases. On May 20, it was announced on TOKYO6's livestream that Rikka would be receiving a larger-scale update to match Karin's and Hanakuma Chifuyu's quality. This would include additional recordings to improve her range with Vocal Mode. The updates covered the following:
Improved voice quality by updating the acoustic model
More faithful to the original recordings' pitch
Voice was clearer and connections were smoother
Pronunciation and vowels were made clearer
Support English, Mandarin Chinese, and Japanese
Improvements made to the Auto Pitch Function
It was also noted that additional songs recorded by Yoshino Aoyama were added to Rikka's data which was necessary for Vocal Mode.
On July 21, Rikka was one of the only AI voice databases not to receive an update for HDVM compatibility (along with Xingchen Infinity). Similarly, she was also the only AH-Software Co. Ltd. AI voice database to not receive Vocal Modes in this update. However, her official Twitter account assured fans that they were still in development and would be implemented at a later date.
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Koharu Rikka Standard Lite may not be used commercially in any way
When using the Lite version of this voice database, "This work uses the Lite version" must be mentioned on any uploads.
Voice database sample
Koharu Rikka Standard Solfège:
Koharu Rikka Standard Lite Solfège:
A preview of Rikka's Synthesizer V Studio AI and Standard voice databases (provided by the Dreamtonics website):
Range: G3 ~ F#5
Lite Version Available?:YesStarter Pack Available?:YesWeb Version Available?: No
Package details as noted:
Rikka is a feminine Japanese voice database that is designed to be suitable for all genres. She has a bright and energetic voice that has solid vocal support, and can also be breathy and nuanced. As expected of an AI voice database, this enables Rikka to sing with a more human-like and realistic voice.
Vocal traits as noted:
Rikka's voice was advertised to be versatile.
Rikka was noted to have a rich middle range.
Phonetic notes as noted:
On December 23, 2021, with the announcement of Synthesizer V Studio 1.5.0, all AI voice databases would be able to use cross-lingual singing synthesis. This allows Rikka AI to be able to sing in not only Japanese but also in English and Mandarin Chinese using this new feature, which is only available in the Synthesizer V Studio Pro Editor.
This does not apply to the Lite version, thus restricting the voice database to Japanese only.
System requirements as noted:
Intel Core series 4th generation i5 (i5-4xxx) or higher
AMD Athlon X4 845, Ryzen series or higher
RAM: 2GB or higher
Disk Space: 1 GB or higher (for installing one voice database)
The amount of space required depends on the number of voice databases installed.
Display: 1280 x 800 or higher
Mac OS X: 10.11 or higher
Linux Ubuntu 16.4 or higher
DVD-ROM Drive (physical edition only)
Internet connection is necessary for activation and obtaining updaters.