Separated by duty, Natsumi receives a telegram and finally reunites with Takimasa on a timid “honeymoon”, where they share simple joys by the sea. That night, quiet stargazing turns into their first fragile moment of closeness, as the distance between them begins to soften.

As their awkward marriage warms, Takimasa’s jealousy nudges them toward deeper intimacy, and a gentle day in town brings them closer. A visit to a tailor run by a young boy leaves Natsumi imagining a different kind of future for the two of them.

Natsumi attends a navy wives’ gathering and grows curious about Takimasa’s past, confiding her worries to a modern, kind acquaintance who helps her seek answers. As doubts linger, visitors from her old life arrive just as Takimasa returns home, setting up an awkward reunion and unspoken tension.

Left waiting in fear after hearing rumors of a sunken ship, Natsumi steels herself for life as a soldier’s wife, only to fall ill just as Takimasa is due home. When he finally returns drunk with a colleague, her hurt explodes, setting off an awkward fallout the next day that doesn’t go the way either of them expects.

Natsumi and Takimasa clumsily go undercover to spy on Fumiko’s café meeting, only to turn it into an accidental date of their own. Afterward, Takimasa suggests visiting Natsumi’s family, leading to his first nervous meeting with her curious sisters.

After growing closer at Natsumi’s family home, the newlyweds return to an adorably awkward morning, learning to rely on each other during year-end chores. As they host a mochi-making gathering, Natsumi tries to nudge Fumiko and Fukami closer, only to glimpse an unexpected side of him when they encounter a troubled boy.

Spending their first New Year together, Natsumi cherishes Takimasa’s promise to pick up their wedding rings someday, then waits anxiously for his return from duty. When he comes home late after an awkward dinner with her father and childhood friend—unable to explain due to secrecy—new worries surface, even as another couple’s relationship quietly moves forward.

Marking their first wedding anniversary, Natsumi helps her sister through childbirth and worries about facing her own future labor alone while Takimasa is away. Meanwhile, Fumiko and Fukami’s matchmaking progresses smoothly, highlighting contrasts between the young couple’s joys and Natsumi’s anxious reflections on family and motherhood.

Natsumi and Takimasa’s plan to see the fireflies is interrupted when he is suddenly called to sea during a storm, leaving her anxious and restless. Sharing fears with Fumiko and guided by wise reassurance, Natsumi, and the young couples around her, face an uncertain future with courage and hope.