birth date of Shimokōbe Yukihira, a samurai of the late Heian and early Kamakura periods, is unknown. He was the administrator (ja) Shimokōbe Manor [ja]...

and the Azuma Kagami refers to a fortification in Koga built by Shimokobe Yukihira before 1180, although it is not certain if it was in this location...

Arinaga Kikkawa Tomokane Okabe Yasaburō Okabe Kiyomasu Hori Fujita Shimokōbe Yukihira Sawara Toshitsura Hangaya Shigetomo Itō Suketoki Usuki Hachirō Ōtōnai...