Sawa Yamauchi (山内 沙羽, Yamauchi Sawa) is Switch and Masafumi's childhood friend. She has a tendency to mix up words, much like Remi, and since middle school was popular with boys. She and Switch held feelings for each other, but were ultimately unable to openly admit them until it was too late. When they were children, Switch asked her whether she would rather marry him or his brother; it is implied that she chose Switch.

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Manga Debut: Chapter 42 (Switch Off, Part 1)

Anime Debut: Episode 24 (Brothers)

(source: sketdance.wikia.com)