Also written 升形. Lit. "square measuring box." A square enclosed by an earthen embankment, stone wall, moat or gates used to protect a castle entrance *koguchi 虎口 and to gather cavalry forces out of sight of enemy forces. The masugata generally includes two gates at right angles to each other, preventing direct entry to the castle. The masugata was the most advanced of such installations; the other main type of protection for a castle gate was the small barrier or compound built outside the gate *umadashi 馬出. The masugata first appeared at the end of the Sengoku period when high stone walls were constructed.
There are two main types: those built outside the castle entrance are called sotomasugata 外桝形, and those constructed inside the main entrance are called *uchimasugata 内桝形. The latter were the more common. Also used for launching sorties out of the castle. A typical size for a masugata was approximately 9 m by 14.5 m (5 *ken 間 by 8 ken): a masugata of this size was known as gohachi-no-masugata 五八の桝形 or gohachi-no-kane 五八の矩.
The gates of the masugata were known as masugatamon 桝形門. The outer gate was called the first gate *ichi-no-mon 一の門, and the inner gate was called the second gate ni-no-mon 二の門. The inner gate was usually the stronger, serving as the main entrance to the castle *ōtemon 大手門. The two gates were aligned at right angles and operated together in two stages like the locks of a canal so that when forces were entering and leaving the castle, the walled court of the masugata could serve as an intermediate gathering place while ensuring the safety of the ōtemon.
An example is the *Shimizumon 清水門, Edo-jō 江戸城, with a small outer triple roofed gate *Kōraimon 高麗門 and an inner two-story tower gate *yaguramon 櫓門. Variations include *yokoya masugata 横矢桝形 where a part of the castle compound jutted out in a squared off configuration. See also *sodemasugata 袖桝形, *hanmasugata 半桝形. The name masugata is said to be derived from the square shape of a Japanese measuring box masu 升, although there is also evidence that the name derives from the second meaning of masu (measure), as the masugata was used to contain and count exact numbers of troops.
