Friendlysoul said:
I am more curious as to the same pain that Hayate and Hinagiku share, which she said when she heard that his parents left him with a huge debt!?
I wanna know what happened to her.
Spoiler Warning:
Kenjiro Hata actually wrote a one-shot a few years prior to Hayate about a girl and her older sister who had been sold off by their parents. He explained later on in an interview that it was Hinagiku and Yukiji. Just thought I'd add on to darkreaper's explanation. ^^