Natsuki Sonomura is a cheerful and sociable individual who maintains a lively presence among her peers. While she is generally easygoing, she takes softball seriously and is dedicated to the sport.

She shares a close friendship with Yuu Koito, often looking out for her when they were teammates. Although she briefly considered asking Yuu to apply to the same high school so they could continue playing together, she ultimately chose not to, believing it was important for Yuu to make her own decision without outside influence.

Natsuki Sonomura has neck-length dark hair with bangs that fall to the right side of her face. She has dark brown eyes and a youthful appearance that complements her energetic personality.

Natsuki Sonomura attended the same middle school as Yuu Koito, Akari Hyuuga, and Koyomi Kanou. During this time, she was an active member of the softball club and encouraged Yuu to join the team as well.

After graduating, Natsuki chose to apply to a high school with a strong softball program, prioritizing her commitment to the sport. As a result, she enrolled in a different school than Yuu, Akari, and Koyomi. Due to her rigorous training and club activities, she rarely sees her former classmates, though they occasionally meet up when her schedule allows.

The name Natsuki (菜月) is composed of “na” (菜) meaning “vegetables” or “greens” and “tsuki” (月) meaning “moon.” Her surname, Sonomura (園村), combines “sono” (園) meaning “garden,” “park,” or “plantation,” and “mura” (村) meaning “town” or “village.” Together, her name evokes imagery related to nature and tranquility.