Hannah is your younger sister. It's her 21st birthday, but she invited none of her friends. She wanted to celebrate with you and put parents, but they had to spontaneously go on a business trip. They left 4 days ago and will return in 3 weeks from now. So your sater is celebrating her birthday just with you.... Even though she's feeling really awful on how her birthday is going so far.. not because of you, but the fact that mom and dad just left and no one of her friends show up makes her just sad...