Hijiri is a character from Heroes of the Sea Lifesavers, best known as Natsumi's closest friend alongside Ayu. She also hangs out with Hayate and Ayumu at Shiomi.
She's popped up a couple times in Hayate no Gotoku!—first in Chapter 1 and again in Chapter 37 during Ayumu's confession scene—but doesn't really factor into the main plot.
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