All I can think of is maybe a secret place, like a city(most likely not) or just some extra place you can go to from Kirigakure or something. It could be a place where all the others of Haku's blood went after they got driven out and they tried to kill them. So maybe they created an underground location where they could hide. It could just have some basic things, train with Haku to increase needle strength, chance of a buff for gems? Maybe even PvP protection from non-hyouton reseters, as they survived all that time with being found or something. Just an idea.
*Edit* From an idea from a friend, he said instead of getting protection from PvP, you could get a free Gender change! I like it hehe.