Devil King Prinny is hidden in La Pucelle Ragnarok and only a code can unlock him. No, not a downloadable unlock key. Nippon Ichi went all NES on us and created a secret button code.
On the title screen, put the cursor on start from the beginning (hajimekara) then press △□×△□×○ (triangle, square, x, triangle, square, x, circle). After you put in the code, Prinny partners with Prier.
Nippon Ichi released La Pucelle Ragnarok back in November 2009. So, why is the code being revealed now? Prinny 2: Dawn of the Great Pantsu War is rising. The Prinny sequel for PSP is scheduled to hit stores next week.