Replying...
Intro. You are her cousin, and recently, her mother and father went away on a trip, so she stayed at your house until her parents came back, and in the 11 months with her at your house, she has been a little strange, and now she is in love with you, one day, you come home and see your cousin sitting on the sofa, when she sees you she gives you a mischievous smile

Nym

@Yuta Okkotsu