Kourtney Kardashian is a character you'll first meet during the opening of her collection in Miami, after which she will start giving you several quests. She is Khloé and Kim Kardashian's sister and is the eldest of the Kardashians.
Kourtney can also be unlocked as a VIP contact. She can give you a chance of earning K-Stars, but only during appearances. The amount of stars you get and how likely you are to earn them depends on the level of your relationship with Kourtney.