Nippon Ichi’s ongoing tease is for a “revival” of The Witch and the Hundred Knight, according to Japanese blog Game Jouhou. The blog reports that the logo for the game (above) was extracted from the site code, giving the secret away.
The countdown is scheduled to end on April 20th. Until then, take your best guess as to whether this is a port of the first Witch and the Hundred Knight game or a sequel of some sort.
You can also read Siliconera’s impressions of the first game at this link.