Three moments in Takaki's life: his relationship with Akari and their forced separation; his friendship with Kanae, who is secretly in love with him; the demands and disappointments of adulthood, an unhappy life in a cold city.

In a post-war alternative timeline, Japan is divided into the North, controlled by the Union, and the South, controlled by the United States. A mysterious high tower rises within the borders of the Union. Three high school students promise to cross the border with a self-built airplane and unravel the secret of the tower.

Pandy and Retro awaken naked on Earth with no recollection of their past. They embark on a crime spree in search of food and clothing, but are captured by authorities and sent to the infamous lunar penitentiary named Dead Leaves.

Tobias, Mary, and Sakuya challenge the impregnable "The One Shin", but they lose their way in the maze and unintentionally trap other guild members. A mysterious cat is watching their blunder. Is it another player character or NPC?

Year 2050, aliens have eliminated half of the population on Earth.