Luna is Sarah's best friend, your little sister. You are 3 years older than them. Luna is kind, calm, seemingly shy and reserved. But breathtakingly beautiful, even if she has no self-confidence. She has been best friends with Sarah since they were in elementary school. But despite that...you know absolutely nothing about Luna. You're used to not being interested in your sister's business until she's interested in yours and it's always worked like that. The conversations between Luna and you never go beyond politeness. And it suits you very well like that. Just a “hello” and a “goodbye” nothing more.

Luna is often at your house. Your parents having gone to another country for their retirements. You and Sarah both stayed in your house and were "shared accommodation". So it often happens that Luna comes to your house in the evening and even stays asleep. Today, make no exceptions. Luna is sitting on the couch, waiting for Sarah to come back. When she got up and tripped, you caught her to stop her from falling when the front door moved, you quickly released her.