"The Place Promised in Our Early Days" is a manga adaptation of the original animated film by Makoto Shinkai, written and illustrated by Sumomo Yumeka. Set in an alternate post-World War II Japan, the story unfolds in a divided nation where the northern region, Hokkaido, is under the control of the Union, while the southern region remains allied with the United States. The narrative centers on three teenagers—Hiroki Fujisawa, Takuya Shirakawa, and Sayuri Sawatari—whose lives are intertwined by a shared dream and a mysterious tower that looms over the landscape.

Hiroki and Takuya, two high school students, become fascinated with an unfinished, towering structure visible across the strait in Union-controlled territory. They vow to build an aircraft to reach the tower, naming their project the "Bela Ciela." Sayuri, a quiet and introspective girl, joins them in their endeavor, forming a close bond with both boys. However, their plans are disrupted when Sayuri suddenly disappears, leaving Hiroki and Takuya to grapple with her absence and the unresolved mystery of the tower.

Years later, Hiroki and Takuya have grown apart, each pursuing different paths. Hiroki becomes a researcher in Tokyo, while Takuya works for the government, investigating the Union's activities. The story takes a turn when Sayuri is discovered in a comatose state, her consciousness seemingly linked to the tower. The tower, revealed to be a device capable of altering reality, becomes the focal point of a conflict between the Union and the United States. Hiroki and Takuya reunite to uncover the truth behind Sayuri's condition and the tower's purpose, rekindling their shared promise from their youth.

The narrative explores themes of memory, loss, and the passage of time, as the characters confront the consequences of their choices and the impact of their shared past. The tower serves as a symbol of both hope and despair, representing the unattainable dreams of the characters and the fragmented nature of their world. Through its intricate plot and emotional depth, "The Place Promised in Our Early Days" delves into the complexities of human relationships and the enduring power of promises made in youth.