Midori Saido is a main character in the anime Musasino! and also appears in the preceding series Urawa no Usagi-chan. She is a high school student and the daughter of a florist from the Higashi-Urawa area, which is part of the Midori Ward. Her character is defined by a consistently laid-back and calm demeanor, and she often serves as a reassuring presence for those around her. She has a fondness for sweets and frequently brings a variety of them to the clubroom, sharing them with her friends. This simple act reflects her thoughtful and caring nature.

Within the story, Midori holds the position of president of the Railway Club, a central setting for many of the series' events. Her role in the club involves balancing the responsibilities of leadership with her family obligations at the flower shop. She is a member of the Railway Club alongside other students, and her interactions with them are marked by her tendency to soothe tensions and maintain a peaceful atmosphere. Her motivations appear to be grounded in supporting her friends and enjoying the simple pleasures of daily life, such as sweets and the company of others.

Midori's personality is characterized by a gentle and comforting quality; she rarely becomes flustered and instead offers calm words of encouragement. She is not depicted as having any outstanding physical or technical abilities, but her emotional steadiness and generosity are her defining traits. The character's name itself is tied to the local geography of the Saitama region, reinforcing her connection to the setting. Throughout the series, Midori remains a stable and serene figure, providing a grounding presence for the more energetic members of the group.