Mamoru-kun 「まもるくん」is a mascot character created by CyberConnect2 (creator of Solatorobo and Tail Concerto) for Fukuoka prefecture’s disaster preparation program. “Mamoru-kun” and “Tail Concerto” (a Playstation game, developed by CyberConnect2) as well as Solatorobo (a Nintendo DS title, also developed by CyberConnect2) share the same universe called “Little Tail Bronx.”

The purple cat is called 「不審者さん」 on pixiv (his actual name is never given), which translates roughly to (suspicious) stranger, prowler, etc. He plays a role in an interactive online game which controls the decisions of the characters in Momoru-kun's universe. You're supposed to make "smart" decisions to evade getting abducted by this fellow. Getting caught gets you "BAD END!!"

Here's a video of some of it in action: http://youtu.be/oEDn4TXPmuU (Spanish)