This watchtower (Kasagi-yagura) was located on the west side of Hon-maru (the main enclosure of a castle). Normally there was nothing stored in this building. The Yagura was a three-story Kake-zukuri (overhang method of construction) and built on top of a huge rock. The landscape perspective from Kasagi-yagura is splendid with a full view of Mt. Kasagi, and that is where the name Kasagi-yagura came from.