The Giraffe's Note is a special item you get when you help the giraffe in Hoya Plains. The giraffe says that she lost her Giraffe's Note and her mother won't be happy with it if she finds out. When you bring it back to her, she tells you that while you were gone, she ended up telling her mother all about how she lost her Giraffe's Note, and tells you that you can keep it.
The Giraffe's Note is a very useful item. When you show it to giraffes, they will lift you up onto higher places that you wouldn't have been able to reach otherwise.