She is Masafumi and Kazuyoshi's childhood friend in the Sket Dance franchise.
Sawa is Kazuyoshi and Masafumi's childhood friend who spend together. She goes to the same school as Kazuyoshi. In her childhood, she is asked by Masafumi who she will marry. Sawa chooses Kazuyoshi. Later on, in the fireworks festival, Sawa and Masafumi get lost, but Kazuyoshi finds them. After Switch's mother takes the picture of them, Sawa hugs Kazuyoshi's arm as they watch the fireworks together with Masafumi.
Unlike Kazuyoshi, Sawa doesn't change much in Switch's story. Even with Masafumi's death, she sees his face every where, so she moves away to get away from the sadness. She will be the same girl.
According to Kazuyoshi and Masafumi, Sawa is a beautiful girl who smiles a lot. She has a beauty mark on the lower corner of her left eye.
Even though she mixes up English words, she has somewhat an air headed personality with a bit of innocence. She is assumed to have a moe personality that affects Kazuyoshi because Kazuyoshi (in his present state) has an affinity for moe characters.
Sawa first appears in Switch's origin story, Switch Off. When Kazuyoshi finds her, Sawa and him go to his house to hang out. She tells him that a stalker is following her. When Sawa points to their old photo of them during the fireworks festival, she suggests that they go to the fireworks festival again. As Masafumi enters the room, he compliments on how cute Sawa's uniform is. Later, Masafumi shows them his new speech software which Sawa hugs Masafumi and says that she will marry Masafumi. The following day, she walks to the mailbox to find a threatening letter from her stalker. Sawa appears at Kazuyoshi's home, and after Kazuyoshi reads the letter, Sawa wants to call the police; however, Masafumi states that the police cannot do anything unless someone gets injured. Masafumi informs Sawa that she needs something to defend herself, and Sawa thinks of a stun gun.
Before Sawa and Kazuyoshi can shop, Masafumi explains that a device that causes a loud alarm is more useful. Sawa compliments on Masafumi's quick thinking, so Kazuyoshi tells them to go shop. Sawa gets sad and eventually goes when Kazuyoshi refuses to go with them. In the city, Sawa and Masafumi get lost; Masafumi talks with Sawa and reminds her that Kazuyoshi always protects them. When Yukino arrives, it starts to rain. Yukino thinks Sawa and Masafumi are on a date, and as she walks towards them, she tells Sawa that she has nothing because her ex boyfriend is only interested in Sawa. Yukino lunges to stab Sawa, but Yukino fatally stabs Masafumi. After the police arrests Yukino and Masafumi dies afterwards, Sawa remains in a state of shock and cannot attend Masafumi's funeral.
When Kazuyoshi arrives and takes on Masafumi's persona, Sawa tells Kazuyoshi that he is punishing himself. As Sawa cries, Kazuyoshi confesses that he loves her, and Sawa also confesses that she loves him back. However, she cannot remain in town because she see Masafumi everywhere. Sadden that she cannot see Kazuyoshi, she walks away.
Sawa is not seen again in the Sket Dance franchise.