The original version of this game is actually a free to play web browser game. This game becomes so popular that they even produced series of anime. Obviously there will be some changes for PS VITA version. This actually enable players around the world who are unable to login into the web browser game based a chance to enjoy the game. The web browser version of the game is only available in Japan. It is still possible to play the web browser version of the game but it will require some technical skills. I suppose part of the attraction of the game is due to the difficulties to login to the game from outside of Japan. Not sure if the PS VITA version of the game will generate similar attraction or not.
Description from Play Asia
Kanmusu fans! Ready to see the battleship girls in action? Kadokawa Games will release the PS Vita version of Kantai Collection - Kan Colle Kai alongside a Limited Edition as well in August! Though it was supposed to come out earlier in May, it's been delayed for three months; regardless, what we know so far seems quite interesting!
Originally a popular free-to-play web browser game based on the dramatic and dynamic relationships that only transforming battleship girls have, Kadokawa Games customizes KanColle for the PS Vita, with a high-tuned system restructure and user interface redesign.
Gamers are going to enjoy new console improvements with novel fleet combat experiences with the introduction of actually controlling the girls, advanced weaponry (like the twin high-angle trajectory gun mount), and special tactical skills (different types of sonar), all involving the Kanmusu!
PS Vita Kan Colle Kai (Japan)