At larger shrines in Japan you will often find a small juyosho「visitors center, 授与所」 which as well as selling general information about the shrine (e.g. maps or a written history of the shrine), usually offers a lucky or blessed trinket that has a deep connection with the location.
That deep connection takes the form of an arrow – specifically a sacred arrow which gave birth to The Young Thunder Prince of Kamo. The legend of this sacred arrow is intertwined with the history of the Kamo Shrines (2 of the 17 World Heritage Sites in Kyoto), as well as the Aoi Matsuri (one of Kyoto’s most famous and largest festivals).
The legend of Kamo’s sacred arrow
Legends says that a young princess found an arrow floating in a stream (which runs through Kamigamo Shrine today), took it home and placed it next to her bed. She then fell pregnant thanks to her new lucky charm, and gave birth to the Young Thunder Prince.
The shrine is popular for people seeking good luck in pregnancy and birth. Visitors can buy blessed wooden arrows, which would usually be then placed in the home. The juyosho also sells lucky charms 「omamori, お守」 promising the same good luck.
See more of the shrine in the Kamigamo-jinja travel guide.
See where I took this photo on Google Maps.