The term "Honmaru" refers to the inner citadel or main keep of a Japanese castle, typically surrounded by defensive walls and moats. It served as the residence of the lord and was the most secure part of the castle, often containing important structures such as the main hall and living quarters. In many castles, the Honmaru is complemented by the Ninomaru and Sannomaru, which are outer baileys that provided additional layers of defense. The design and layout of the Honmaru reflect the architectural style and military strategies of the Edo period, showcasing the importance of fortifications in feudal Japan.