High-rise Invasion

is a manga series written by Miura Tsuina and illustrated by Oba Takahiro that was serialized on Manga Box from December 5, 2013 to April 4, 2019. A 12-episode Netflix ONA by Zero-G was released on February 25, 2021.

Plot
High-school girl Yuri suddenly finds herself on the rooftop of a high-rise building. She's trapped in a bizarre world surrounded by skyscrapers, where a masked man cracked open a man's head with an axe before her eyes. She makes fast friends with another girl, Nise-chan, and they traverse the world together, seeking a way to end the mysterious realm.