Sawa Echizen is a kind-hearted first-year student at Warabi Seinan High School, recognized by her lanky grey-brown hair and deep brown eyes. Her defining trait is unwavering support, especially for her childhood friend Nozomi Onda, whom she's known since preschool. Echizen consistently encourages Onda's football journey, from childhood games to comforting her after setbacks like failing to make official rosters. She demonstrates deep loyalty through actions like visiting a temple to wish for Onda's tournament inclusion.

Beyond her supportive nature, Echizen holds unconventional interests, including a noted appreciation for splatter and slasher films, with specific admiration for Jason Voorhees from the *Friday the 13th* franchise.

Initially serving solely as the manager for Warabi's girls' soccer team, Echizen handles duties like video analysis, nutritional planning, and organizing activities such as cooking classes. She scrutinizes matches critically, noting tactical elements like stamina disparities. Her role evolves significantly as she transitions from managerial duties to becoming an active substitute player. She participates directly in practice to prepare for competitions like the JKFB Interleague, following her deepening involvement observing events like fundraising futsal tournaments and Saitama preliminaries.

Echizen's relationships reflect her character:
- She calls Onda "Non-chan" and remains her steadfast confidante, though expressing frustration when Onda neglects practice.
- She admires opponents like Tae Kokubu for their strength and talent.
- She develops camaraderie with teammates, calling Sumire Suou "Su-chan" and relying on her runs, while viewing Midori Soshizaki as dependable.

Key interactions include meeting Kazuo Takahagi, coinciding with her increased on-field participation. Her narration provides perspective during team matches. She offers heartfelt encouragement to Onda, emphasizing collective support and shared excitement for Onda's soccer future.