Kumo no Mukou, Yakusoku no Basho

In a divided Japan, Hiroki and Takuya build a plane and promise their friend Sayuri that they will fly together to the mysterious tower visible across the border. Her sudden disappearance breaks their plans, and the boys eventually drift apart.

Years later, Hiroki learns that Sayuri has been trapped in sleep, her dreams entangled with the tower and other possible worlds. Reviving their abandoned aircraft also means reviving a promise neither boy has forgotten. But bringing Sayuri back may place far more than their lost friendship at risk.