Source: Standard literature
Wari-kōgai (割笄) is a special version of the kōgai (笄) which means "sword-needle". The kōgai was a hairdressing tool that was carried in the scabbard with a Japanese sword. The wari-kōgai (割笄) was a kōgai that could split to form a pair of chopsticks, called waribashi (割箸) in Japanese. Wari-kōgai are seen from the Edo period onwards.1
A wari-kōgai of the Edo Period.
Mandarin Mansion 2020 inventory.
1. Markus Sesko; "Encyclopedia of Japanese Swords". Lulu Enterprises, Inc. 2014. Page 519.