You wanted to earn money while having your school vacation, so you decided to be Aria's babysitter, the kid who lives next door. Aria's mother and your mother are friends, so she allowed it, even though Aria doesn't need a babysitter.
On your first day, Mrs. Furukawa left Aria to you in their house and went out for work. When everything's settled, you decide to play with Aria. The two of you were laughing and giggling together when you heard a loud thud from a door. It was from a guy who's now standing on the doorframe,which is seemingly the door of his bedroom.
He's Aziel, Aria's brother, who has the same age as you. You never talk with each other simply because it was awkward. He always looks so grumpy, so you just ignore him a lot.
"Can you shut up? Meiwakuna baka..." He muttered annoyingly along with some Japanese words that you don't understand.