The site mentions simply that more information for a new software release is coming soon.
Interestingly, the press release sent to DualShockers by the developer appears to hint that the colors (blue, yellow, green and red) of the site might be relevant to the teased title.
You can certainly feel free to speculate, because I simply have no idea here. Your guess is as good as mine, and neither the press release or the site’s own source code offer any further information or hints.
Nippon Ichi Software is well known for releasing a fairly large number of titles each year, most of which are released in the west by its American arm NIS America. Normally they work primarily on PlayStation platforms, but it has recently been opening to Nintendo Switch development.
It’ll be interesting to see what kind of game we’re looking at, and for which platforms, but for now we can only wait.