Cinderella Found Her Prince is a Manga/Manhwa/Manhua in english language, Manga series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

My little sister and I looked up at a high-rise apartment building, touching the clouds like a castle would. Even if there was a princess living in there, it didn't have anything to do with us, merely an unreachable existence---Or so we thought. With a meeting by pure chance, I ran into Shindou Rei, and realized. The Rei in front of me wasn't a princess, or theuntouchable idol at school, but just a cute girl you could find anywhere.