本ほん丸まる

noun

inner citadel; main enclosure

Historical term for the innermost, most fortified part of a Japanese castle. Still used in historical contexts and as a metaphor.

• 姫ひめ路じ城じょうの本ほん丸まるはとても広ひろい。

  The inner citadel of Himeji Castle is very spacious.

noun

core; center; crux

Figurative extension of the castle term: the most important part, the heart of a matter, or the main focus. Often used in business, politics, or strategy.