Ishiotoshi

What an ishiotoshi is

An ishiotoshi is a projection carried out beyond the stone base of a turret or Tenshu, with an opening in its floor through which stones or arrows could be dropped on anyone climbing the wall below. From outside it reads as a small oriel.

Records note which faces carry them. The small keep at Matsuyama Castle in Ehime Prefecture, reconstructed in 1967, is described as a two-tier corner turret at the south-east angle of a keep group on a square plan, Irimoya-zukuri with Hongawarabuki, a Chidori-hafu on the south of its lower tier, walls in Shikkui with Shitami-itabari at the base and the eaves soffit plastered over, and hooded projections of this kind on the two outward faces. Only the sides facing away from the castle interior have them.

The south corner turret at the same castle has one at each corner of its lower tier, with a Kōran round the tier above.

Long ranges carry several. The ten-bay corridor at Matsuyama is described as a single-tier Tamon-yagura linking two corner turrets, with three hooded projections along its west face.

Shape and placement

The hooded form recurring at Matsuyama has a small roof over the projection. Ozu Castle in the same prefecture uses another: the city's cultural property page records three of the flared type on the south corner turret of the third bailey, widening downward like a pleated skirt.

Corners are favoured because the angles of a stone base create blind spots. The west adjoining turret at Matsuyama is described as having one at its angled south-west corner, forming a distinctive Masugata together with the gate to the west. The position covers the point where the approach changes direction.

On site, look up where wall meets stone base. Where the wall oversails the stone with a gap or a small roof beneath it, that is the feature. Inside, the floor opening looks straight down the face of the wall.