Natsume Sorayama, a high school sophomore at East School, transferred during her freshman third semester from the Kansai region. She belongs to the floriculture and horticulture club, managing a field near the school swimming pool for summer practical training. Natsume shares vegetables harvested from this field with swimming club members, inviting them to meals.

Physically, she stands 149 cm tall, weighs 38 kg, with measurements of B80/W52/H78. She has brown eyes and brown hair, often styled in twin tails or hair loopies. Her appearance is slim, pale, and teen-like. Her typical attire includes a sailor school uniform, hoodie, sundress, T-shirt, thigh-high stockings, or sport bloomers, suited to gardening.

Kind, modest, neat, and friendly, Natsume is noted by others for a subtly unusual aspect to her behavior. She forms a connection with Hajime Saisho of the swimming club, developing special feelings for him before transfer student Asa Mizushima arrives.

During summer, concealed in a sunflower garden by the pool, Natsume overhears intimate conversations between Hajime and Asa and willingly participates in their subsequent sexual activities. Later, at a hot springs outing, she confides in Asa about her longstanding romantic feelings for Hajime. This leads to an agreement between them to share Hajime equally until summer's end, knowing both must leave him when the season concludes.

As summer progresses, Natsume spends time with Hajime while confronting the impending separation. Several years after their summer arrangement, she reunites with Asa at a train station to see Hajime again. Her background focuses on her school activities and relationships during this period. Her development centers on navigating complex romantic dynamics, shifting from a reserved gardener to an active participant in a shared relationship, culminating in this later reunion.