Hiroki Fujisawa and Takuya Shirakawa share a deep admiration for their classmate Sayuri Sawatari and the towering Ezo Tower looming in the distance. Inspired by this unreachable marvel, they embark on building an aircraft, the Bella Ciela, using a recovered drone, with the singular goal of soaring to the tower's summit. Their romantic pursuit intertwines with a divided Japan, split between warring factions near the tower's base—the boundary between American-controlled Southern territories and the Soviet-occupied North. As they involve Sayuri in their aerial ambitions, a tragic twist separates her from them, revealing a hidden reality: Sayuri has been in a mysterious coma for three years, a condition cryptically tied to the enigmatic tower they aimed to conquer together.