The website is
here.
Much of the text are actually just PNG images so I can't use Google Translate to get the just of it, but here's what I've gathered.
Not 100% sure if Hikari is available to the public. When you go to the VoiceText main website, this page states that VoiceText is not a commercial product, but a tool to be sold to companies for whatever purpose. There is, however, a few products using this software that they sell, but none that are the base VoiceText product.
I can't say if this extends to Hikari and the other characters listed on the page linked above, I could sort of see the company trying to cash in on the popularity of Cevio and Voiceroid, but I'm honestly not sure.
I can't translate the character bios, but from left to right, their names are: Hikari, Takeru, DJ Shogo, Hina, Kouta, Ema, Tsuna, Show, Kanna, & Nou.
There is also a sort of voiced acted comic linked to these characters that uses their voicebanks, called "On Air", which can be listened to
here.
Other than that, if you scroll to the bottom of the page (Or click the Concept button on the left) you can demo Hikari's talk voicebanks (She currently has 4) using an in-browser TTS module.
I'll keep you posted if I find anything else.