This will be NIS's first visual novel, a popular genre in Japan, published in the United States. According to the announcement, players can play with a Prinny as the main character, and they will be trying to unravel an assassination attempt. A special clock allows the Prinny to take over other characters minds and bodies, allowing the player to learn the truth and unravel the mystery.
The screens above are in Japanese; NIS promises to release localized ones as they become available.
Disgaea Infinite PSP North America Announcement [NIS America]