Keroppi is having a bad day and wishes he could be dependable like Hello Kitty. Luckily, the magical fish hears of this wish and grants it. Without warning, Keroppi is now Hello Kitty, and Hello Kitty is now Keroppi. By magically switching bodies, they soon find out they need to switch back fast. Will Keroppi be dependable and find the fish in time so Hello Kitty can make it to her event? Only time will tell.