Far in the future humans were at war with robots and the machines won. The humans hid themselves away from the robots and built villages hidden in the ruins of society. In this future a normal human girl named Nanami has been living a poor but content life with her older sister and her childhood friends.

However, on her birthday a tragedy happens. While Nanami is away her village is attacked by robots and her sister is captured. She blames herself, 'If only I wasn't away from the village'.

Then as if being led by fate she meets a robot called 'Kagome'. He has the power to grant Nanami's wish. The power to grant her wish of 'if only' and return her to the past.

Nanami and Kagome go on a journey in order to change the future of despair into hope.