JAPANESE CULTURE, EXPLAINED
天守
A tenshu is a multistorey keep within a Japanese castle. It stands among gates, turrets, ramparts, moats and palace buildings that served other functions in the complex.
Keeps stored supplies, served as wartime lookouts and displayed a ruler’s authority, with uses varying by castle. Residential and administrative work took place in palace buildings. At Matsue, these stood in the second and third enclosures.
| Elevation: five exterior tiers, bottom to top | The Great Keep’s roofed stages; the lower connecting building is at right. |
|---|---|
| Section: six interior floors, bottom to top | The third floor lies within the second roof tier. |
| Third floor | An opening in the southern chidori gable admits light. |
Exterior tiers are the roofed stages seen from outside; floors are the levels inside. Matsumoto’s keep has five tiers and six floors because its third floor lies within the second tier’s roof space. An opening in the southern chidori gable admits light to that concealed level.
| Hanegi | Thick members extending radially outward to support the eaves. |
|---|---|
| Igeta beams | Large beams arranged in a square grid, distinct from radial hanegi. |
Radial hanegi members on the sixth floor of Matsumoto’s Great Keep use leverage to support the heavy tiled eaves. Weight toward the centre acts on their inner portions while their outer ends support the eaves against drooping. In the interior photograph, distinguish these radial members from the large beams arranged in a square.
A bōrō keep has a smaller lookout above the large roof of the lower building. An irimoya roof combines a gabled upper part with lower hipped slopes. Inuyama is a bōrō example: its top floor has a veranda and railing, above three exterior tiers, four above-ground floors and two basement levels. Historic Nagoya exemplifies the sōtō form, whose tiers diminish more regularly towards the top.
Azuchi Castle, begun in 1576, made imposing stone walls and an elaborate keep a prominent display of authority. Further keeps followed at Himeji and elsewhere. In 1615, the one-castle-per-province order and warrior-house laws restricted new castle construction and required repairs to be reported. Further construction and rebuilding took place under these shogunal controls.
Matsumoto’s keep faced sale and demolition in 1872. Ichikawa Ryōzō proposed exhibitions inside it; five were held from 1873 to 1876, which the official history links with its survival. Later decay and leaning prompted fundraising led by Kobayashi and others, with repairs completed in 1913. These local efforts preserved the keep through successive repairs.
Himeji retains historic timber construction through successive repairs. The city records dismantling the main keep in 1958, reassembly from 1959 and completion of work on the keep group in 1964. Replacement and structural reinforcement belong to the building’s conservation history.
Nagoya’s timber keep was built in 1612 and destroyed in an air raid in 1945. The 1959 replacement used steel-framed reinforced concrete, recreating the earlier exterior around exhibition space. Himeji’s dismantling repairs, by contrast, conserved a surviving timber structure. Nagoya’s proposed timber reconstruction draws on measured drawings, photographs and records and remains a proposal.
The third floor lies inside the second roof stage; roof tiers and interior levels count different things.
They use leverage: roof weight toward the centre helps their outer ends support the tiled eaves.
Himeji’s work conserved surviving historic timber construction; Nagoya built a steel-framed reinforced-concrete replacement after the original was destroyed.
