Masami Fujii is a fifth-grade student in class 5-B at Keishin Private Academy, serving as the shooting guard wearing jersey number 13. She stands 143 cm tall with distinctive violet curly hair, usually styled in a left-sided ponytail, and matching violet irises. Her family operates a restaurant on the same street as the Nagatsuka family's business, resulting in a longstanding rivalry between the establishments. This fuels Masami's intense personal drive to surpass Saki Nagatsuka, a rivalry largely one-sided from her perspective.

Obsessed with defeating Saki, Masami joined the Keishin Girls Mini Basketball Team after seeing Saki's skill. To gain an edge, she rigorously trained in long-range jump shots, specifically targeting distances beyond the standard three-point arc. While this skill has limited application in mini-basketball where three-point rules don't exist, it occasionally disrupts opponents' zone defenses.

Initially stubborn and fiercely competitive, Masami extended her rivalry beyond basketball into academics and cooking. After repeated competitive losses to Saki and her team, Masami recognized flaws in her attitude and shifted her focus towards teamwork and personal improvement instead of solely defeating Saki.

During the fifth-grade basketball team formation, Masami joined a new group challenging the sixth graders. Her role involved fostering a competitive atmosphere that pushed both teams to refine their fundamentals and strategies. This integration into the team structure marked her evolution from a solitary rival to a collaborative player contributing to collective growth. Her name, meaning "elegant, graceful" and "beautiful," contrasts with her initial combative nature, reflecting her progression towards genuine sportsmanship.