Nippon Ichi Software just opened a new teaser website for a “new title.” The count down indicates a reveal on April 21st at midnight Japan time, which means April 20th at 11 AM EDT/4 PM BST.
The game seems to be a console title as indicated by the “consumer” part in the address, which in Japan identifies console productions.
At the moment nothing else is known, as the website is just a completely black page with the “Re” wording and the counter.
Update: the Japanese blog Sokuho@Hokanko(alt) solved the riddle in a rather unorthodox way. They unpacked the SWF file of the count down, and found out the following logo, indicating the game as The Witch and the Hundred Knight: Revival.