DEX and DAINA were given the theme, 'The Fox and the Hound', at the suggestion of Kenji-B. They were intended to be counterparts which complement each other. DEX was based on the Hound character of the story and has more "wolf"-like traits. Kenji said that DEX and Daina were a pair, but were not twins. When asked about the aims of both DEX and DAINA, it was stated that the pair were targeted towards fans and designed to give producers the voices they needed. The theme of "fox and hound" was one of many suggestions put forward, but it was the one that stayed due to a fondness among the group despite being taken lightly. The design was chosen after the team adored the primary sketches by Steel.
EmpathP remarked that they knew many would not like the designs and focused on the vocals instead.
After negative reactions from distributors, DEX was also given an alternative design without the animal traits, but still retains the theme of The Fox and The Hound. This was done to appeal to non Japanese-styled art fans. The alternative design featured DEX without his wolf ears and tail. The ears were replaced by black headsets with a yellow wolf on it. This version of DEX appears on the boxart.
Older concepts were revealed during a November 2015 livestream. This included DEX as a hunter instead of a kemonomimi, in case Zero-G wished to scrap the 'Fox and Hound' theme. However, Zero-G liked the designs, and they were kept as alternate fantasy illustrations, complementary to AVANNA. According to AkiGlancy, Steel added more detail to the hunter design then the regular art. The regular art was cel-shaded because Zero-G themselves preferred it.
Dex and Daina were put on sale within a short time of being released, noting that they were Zero-G's (then) current best selling product.
Both Dex and Daina proved to be very popular and despite their recent release, both nearly claimed the no.1 spot from Avanna in the 2015 most popular product for Zero-G. Dex held the no.2 position. Zero-G also highlighted once again how well the pair were selling being "big news", noting their sales with the words "red hot" in red text, which had never been seen before.
First male VOCALOID4 from Zero-G.
First male native English VOCALOID to be available for Mac.
One of the first Zero-G VOCALOIDs to be available for Mac.
DEX and DAINA were the first counterparts of VOCALOID4.