There was an eight month interval between the release of Dragon Quest IV: Chapters of the Chosen and Dragon Quest V: Hand of the Heavenly Bride in Japan. North America might not have to wait as long for the next game in the Zenithia trilogy since Dragon Quest V: Hand in the Heavenly Bride was just rated by the USK, Germany’s ESRB equivalent. Since Dragon Quest V has a rating it must be well in development.
Also found on the USK is another Square Enix game, My Pet Shop. I doubt Square Enix is making a Pet Shop game just for Europe. This title probably is Pet Shop Monogatari developed and released in Japan by their wholly owned subsidiary Taito.
Images courtesy of Square Enix.