Taeko Okajima is a 27-year-old, independent woman who spent her entire life in Tokyo. Looking to unwind from the rush of the big city, she decides to visit her family in the country to help out during the harvest.

On the train there, Taeko vividly recalls her memories as a schoolgirl in the initial stages of puberty, as if she is on a trip with her childhood self. A young farmer named Toshio picks her up at the station, and they quickly develop a friendship. During her stay, Taeko forms strong bonds with family and friends, learning the contrasts between urban and rural life, as well as the struggles and joys of farming.

Nostalgic and bittersweet, Omoide Poroporo takes on Taeko's journey as an adult woman coming to terms with her childhood dreams compared to the person she is today.