"Rose Guns Days: Fukushū wa Ōgon no Kaori" is set in a post-World War II alternate timeline where Japan is divided and occupied by three foreign powers: the Principality of Yue, the Republic of Remano, and the State of Daifugo. The story unfolds in Season City, a bustling metropolis under the control of these foreign forces, where the native Japanese population is marginalized and oppressed. The narrative centers on Leo Shishigami, a young man who becomes entangled in a web of revenge, loyalty, and survival after a tragic incident involving his family.

Leo’s life takes a drastic turn when his sister, Yuki, is killed during a violent confrontation between the Japanese resistance and the occupying forces. Seeking justice, Leo aligns himself with the resistance group known as the "Japanese Liberation Front," led by the enigmatic and charismatic Ryūnosuke Akagi. However, Leo’s path is complicated by his growing relationship with Rose Haibara, a skilled and determined woman who operates as a gun-for-hire. Rose, driven by her own mysterious past, becomes both an ally and a source of conflict for Leo as their goals and methods often clash.

The story delves into themes of revenge, identity, and the moral ambiguities of resistance. Leo’s quest for vengeance against those responsible for his sister’s death leads him to confront powerful figures within the occupying forces, including the ruthless General Huang of the Principality of Yue and the cunning diplomat Claude of the Republic of Remano. As the plot progresses, alliances shift, and the line between friend and foe becomes increasingly blurred. The narrative also explores the internal struggles of the Japanese Liberation Front, as factions within the group debate the ethics of their actions and the cost of their fight for freedom.

Key supporting characters include Stella, a former actress turned resistance fighter with a tragic past, and Keith, a skilled sniper with a pragmatic approach to the conflict. The interplay between these characters adds depth to the story, highlighting the personal sacrifices and moral dilemmas faced by those fighting for liberation. The manga balances intense action sequences with moments of introspection, creating a layered portrayal of a society grappling with occupation and resistance.

"Rose Guns Days: Fukushū wa Ōgon no Kaori" is a gripping tale of revenge and rebellion, set against the backdrop of a fractured and oppressed Japan. Its intricate plot, morally complex characters, and exploration of the human cost of conflict make it a compelling addition to the genre of historical and political manga.