Ayu is a character from Heroes of the Sea Lifesavers and part of Natsumi's friend group alongside Hijiri. She goes to Shiomi Academy along with Hayate and Ayumu, though she doesn't play a major role in the main story.
She does show up briefly in Hayate no Gotoku! Chapter 1 and Episode 37, appearing in a flashback where Ayumu asks Hayate if he can take a photo sticker with her. Beyond that cameo, she's mostly background.
Content compiled by AnimeList.moe from publicly available sources.
