Hello Kitty: Big City Dreams takes the cute little mascot of Sanrio where no kitty has gone before: out of Sanrio Town! You see, Hello Kitty has gotten bored of life in the middle of scenic nowhere and craves a more exciting lifestyle in the big city. But her main reason why she's moving to the big city is because she's always wanted to live in a penthouse on the top floor of her new apartment building. With the help of her friends - both old and new - she just might make it in the big city. And, to coin the old phrase, if you can make it there, you can make it anywhere!

As Hello Kitty, the player explores a massive city, full of streets, buildings, attractions, shops... practically anything that a city this large can offer. Within these localities lie a series of mini-games which can help Hello Kitty earn friendship points, which in turn entitle Hello Kitty to ride public transportation, purchase new stuff, customize her apartment, and move her one step closer to her dream penthouse.