Synopsis

A global catastrophe begins with the appearance of massive towers, causing monsters to emerge and wipe out a third of humanity. Individuals known as Tower Walkers gain abilities within these towers and become humanity's last hope. Inside, they find a 'Return Stone' that can send users back in time but with uncertain consequences regarding the timeline. While they debate using the stone, another tower impact devastates the outside world, forcing the Tower Walkers to decide whether to use the stone or face certain death in the current timeline.