Set in early Showa-era Japan, Butterfly is a young geisha apprentice living in a geisha house. From childhood, she has harbored a deep, unspoken love for Chinatsu, a skilled tattoo artist who lives nearby. Unable to openly receive the tattoos she yearns for, Butterfly finds joy instead in the painted sketches he draws on her skin, particularly the butterflies that become a symbol of their bond. Their relationship deepens over time, and the two eventually marry and begin living together, navigating the quiet happiness of their domestic life against the backdrop of a rapidly changing society.

Their peace is shattered by the onset of war. Chinatsu receives a draft notice and is forced to leave for the front, promising Butterfly that he will return. The narrative follows Butterfly as she clings to that promise, waiting faithfully for his return while confronting the loneliness and uncertainty of the era. The story builds toward the emotional climax of his fate, testing her devotion and resilience in the face of separation and loss. The completed two-volume series weaves a gentle romance with the historical tension of the period, focusing on the strength of an unwavering bond tested by time and circumstance.