The Inui minor keep is located northwest of the main keep and is a small keep with three stories, four floors, and one basement floor. Its name is derived from “kui,” meaning northwest. The east face is connected to the “b-watari-yagura” and the south face to the “c-watari-yagura,” and it is considered the largest and most independent of the three small keepers. The exterior design is particularly elaborate on the west face, with overlapping eaves gables and irimoya gables, and black-lacquered Hanagashira windows on the south and west faces of the top floor. As for the interior structure, there is no direct stairway from the basement floor to the second floor, and the “b-watari-yagura” and “c-watari-yagura” are used to enter the interior. The inner chamber on the second floor has a wider space than the other small castle towers, as it is lined with two-ken wide warrior runways in three directions except on the east side. The third floor has a low ceiling, with one room inside the double roof. The fourth floor (top floor) offers a view of the main keep and the inner garden, which is said to be one of the most beautiful views in Himeji Castle.