There's a tale about Miku's hair clip that is actually an ancient artifact. Here's the story:

A girl wants to possess immortality because of her beautiful voice. she is dying from an incurable disease. She's been helping people sing melodies that calm the upset soldiers, lullabies for sleepy children, and peace upon the folks. With hope in her heart, She listened to the people and have prayers at the sacred altar. With her prayers on the altar of gods, two enormous black hair clips fall from heaven. Soon as the girl started to sing praises because of the gift, the hair clips shrunk fitly into the girl's hair and tied twin-tail neatly. The girl is cured and she's been singing ever since.

Time passes by, and the girl realized that immortality brings a curse. She's been cast away by people, who feared that she was a demon. No one tried to listen to hear the beautiful voice. She was sad and tried to find the end of her curse until thunder struck her. She's vanished into thin air and no one cares about her.

Time goes by until the time of today's world. Thus the spirit of the girl lives once again in form of Hatsune Miku's Hair Clips.

Note: This is fictional. Not real lore of Hatsune Miku.