Cinderella wa Sagasanai.

Overview

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 doesn't have anything to do with us, merely an unreachable existence---Or so we thought. With a pure chance meeting, I ran into Shindou Rei, and realized. The Rei in front of me wasn't a princess, or the untouchable idol at school, but just a cute girl you could find anywhere.

Source: AniList