"Allison" is a manga adaptation of the light novel series by Keiichi Sigsawa, illustrated by Kouhaku Kuroboshi. The story is set in a fictional world divided into two nations, the Roxchean Federation and the Sou Beil Alliance, separated by a vast river and locked in a decades-long cold war. The narrative centers on Allison, a skilled and daring pilot in the Roxchean air force, and Wil, her childhood friend and a reserved but intelligent student. Their lives take a dramatic turn when they uncover a long-buried secret that could end the war between their nations.

The plot begins with Allison and Wil embarking on a journey to locate a legendary treasure rumored to hold the key to uniting their divided world. Their quest leads them across treacherous landscapes, through political intrigue, and into encounters with various factions seeking to exploit the treasure for their own ends. Along the way, they face challenges that test their courage, resourcefulness, and loyalty to each other. The story explores themes of friendship, sacrifice, and the futility of war, as the duo strives to bridge the gap between their nations and bring about peace.

Key characters include Allison, whose boldness and determination drive much of the action, and Wil, whose analytical mind and calm demeanor provide a counterbalance to Allison's impulsiveness. Supporting characters, such as Benedict, a seasoned soldier with a mysterious past, and Fiona, a young girl caught in the crossfire of the conflict, add depth to the narrative. The manga maintains a steady pace, blending action, adventure, and moments of introspection, while staying true to the source material's focus on the bond between its protagonists and their shared mission to change the world.