割笄 Warikogai or Sakikogai / Split Hairpin
What is Warikogai or Sakikogai in Japanese Katana terminology?
This is a type of Kogai (hairpin), which is split into two parts like chopsticks. The Kogai was originally a tool used by samurai to arrange their hair and clean their ears, among other grooming purposes. It was equipped with a small handle in the Uchigatana Koshirae (sword mountings) in the late Muromachi period, but the demand for it as a decorative item increased in the Edo period. The Warikogai also became popular as a decorative metal fitting for short sword mountings.