Under the names of "SUGAR" and "SPICY", the vocals were introduced with a demo video on June 15, 2016. At the time, their designs were not revealed. They were announced to be developed by Internet Co., Ltd in collaboration with MTK and were confirmed to release on July 30 that year.
On June 30, the designs were shown and it was revealed that SUGAR and SPICY were the names of the voicebanks for the character Otomachi Una. It was confirmed that she was voiced by Aimi Tanaka, a Japanese voice actress best known for voicing Umaru Doma of Himouto! Umaru-chan. Her downloadable version was confirmed to release on July 30 while her packaged version was to be released on August 4. A starter pack was also confirmed to be available. According to her official website, two more demos were to be expected. Official MMD models, motion data, and video materials were also be released for her.
In total the package offers the equivalent of 2 additional voicebanks achievable via XSY. The total tone variation offered by the package comes to a theoretical 4 voicebanks in total.
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.
Otomachi Una is one of the top vocals within the XSY group "Internet" as a secondary vocal with use for XSY.
Her vocal range and tempo cover the ranges of most other vocaloids within the group.
In addition, she has two vocals that give a wide choice of tones between them.
Software issues as noted:
Similar to other child vocals such as Kagamine Rin/Len and Ryuto, she is voiced by an adult. This means she will have a limited on how realistic her portrayal of a 11 year girl because her vocal is done using voice acting methods.
As noted in a comparison by VOCALOIDTV, the overall package has noticeable issues with the GWL function, producing a strong warp noise when overusing it.