This sequel to the PS Vita original is launching in Japan on October 13th and with the original released in the west, its likely that western gamers will have access to the game in the future. NeoGaf member Parakeetman rounded up released information on the title and that will be listed below the source link.
Source: NeoGaf

Seems like at the Kadokawa presser today they finally released news on the Japan release date for Demon Gaze 2. October 13th, 2016
Info came from a JP twitter user thats attending the event and has been tweeting out other info from it.
Other source

http://gamestalk.net/post-60741/

Demon Gaze II will launch for PS Vita in Japan on October 13 for 6,300 yen, Kadokawa Games announced at its summer press conference today.
Pre-orders will include a “Best Selection Demon Gaze Music” CD featuring music from Demon Gaze and Demon Gaze II.
The publisher said the Demon Gaze series was conceived as a trilogy, and that they’re aiming at a million sales worldwide for the franchise.

*Credits to Gematsu
Official JP HP
http://demongaze.jp/dg2/
*Site has been updated.
Seems like preorders will be coming with a best selection Demon Gaze music from I & II.

http://www.4gamer.net/games/323/G032387/20160613047/
Debut Trailer
https://www.youtube.com/watch?v=oOIGzkDSzN8