Officially introduced in January 2011, CUL started off as the mascot for the television special VOCALO Revolution and utilized the voice of VY1 for her promotional appearances. On June 8, 2011, Yamaha announced that CUL would become a real VOCALOID, with Eri Kitamura as her voice provider. The publisher was confirmed to be Internet Co., Ltd. On November 4, 2011, her first demo, a cover of a V3 GUMI demo "A Flash of Summer", was released on YouTube. Internet Co announced on twitter that CUL would be released around December 22. A second demo was also uploaded, this time a cover of V3 Gumi demo "Nightmare." Her third and fourth demos have also been uploaded.
In October 2014, when asked in an interview if any vocal produced any hard labor, Noboru mentioned that CUL was a hard Vocaloid to produce as when synthesized she gave a result that was under quality. Noboru mentioned they had to scrap her original vocal and rebuild it from scratch. They had to re-build the vocal twice, though no re-recordings were involved.
In July 2013, Internet co.,Ltd announced a Mac update of this product for the VOCALOID NEO engine.
Once imported into VOCALOID4, she becomes available for XSY. However, she has no XSY capable voicebanks she can use of her own as she is a single voicebank release. Therefore users will have to purchase addition voicebanks not belonging to Cul at all for use of XSY from her XSY group "Internet".
From Ver.4.3.0 of the Vocaloid engine, a XSY group "Internet" was added to Vocaloid. All vocals within the "Internet" group can XSY with each other. This vocal release is part of this group. If a User owns one or more vocals within the "Internet" group, XSY between them will open up as a result of owning this release.
The "Internet" group is currently the largest XSY group at 29 voicebanks. If old versions that have since been re-released are removed, there are currently 21 unique voicebanks. These are; "Gackpoid Native", "Gackpoid Whisper", "Gackpoid Power", "Lily Native", "Lily", "Cul", "Kokone", "Gachapoid", "Chika", "Otomachi Una Sugar", "Otomachi Una Spicy", "Megpoid Native", "Megpoid Sweet", "Megpoid Adult", "Megpoid Power", "Megpoid Whisper", "Megpoid Nativefat", "Megpoid Mellowadult", "Megpoid Powerfat", "Megpoid Naturalsweet" and "Megpoid Softwhisper".
In total if user was to own every VOCALOID3 and VOCALOID4 XSY capable INTERNET co., LTD vocal, this offers the equivalent of 812 additional voicebanks achievable via XSY. The total tone variation offered by the combined packages comes to a theoretical 841 voicebanks in total.
Note that Users of the updated XSY list have to understand that as confirmed by Internet co., Ltd themselves, depending on the combination of the two vocals a level of extra unwanted noise may be generated.
Another note worthy detail on V4 and later vocals compared to V3 vocals within this group is that Internet Co., Ltd. increased the number of triphones from Chika onwards. Thus, many newer vocals do not match sound-for-sound with the older pre-Chika released vocals.
Post VOCALOID4 releases were also developed with XSY in mind, so are better for XSY then the older VOCALOID3 releases.
In addition to not being built with XSY in mind, VOCALOID3 packages with only 1 vocal in their contents that were released may be even more problematic for XSY. Internet co often made multi-pack releases have a quality that made switching mid-song less noticeable between voicebanks, making them slightly better for XSY then single vocal releases.
Note that also "GWL" does not become viable for use with any V3 vocals used as the primarily vocal. This should be considered when using any vocal for XSY within the "Internet" group from V3.
CUL's vocal is one of the vocals within the Internet group who is known to have strange effects on other vocals due to its heaviness compared to many other vocals within the group. It is quite easy for her to impact quality in certain ranges and users need to be aware of this when XSYing her.