What irigawa means
An irigawa is the corridor-like zone around the outside of a building or reception room, lying between the outer veranda and the inner rooms. The name is said to reflect its position one step in from the veranda. It is often floored with tatami, in which case it is much like a tatami corridor.
Castle keeps, palaces and shoin halls often have plans in which the central rooms are surrounded by an irigawa. In houses, an irigawa at the front or back of the principal reception room separates it from the outside air and serves as a passage or waiting space. A veranda enclosed within outer sliding doors is sometimes called an Uchien, and usage can overlap, but records usually use irigawa for the zone between reception room and veranda.
Reading the records and the building
Records describe an irigawa around or beside rooms. The first floor of the keep of Inuyama Castle, a National Treasure, is ringed by an irigawa two bays wide enclosing four rooms, the principal one a jōdan-no-ma. The main house of the former Aikawa family in Isesaki, Gunma, has a one-bay tatami irigawa along the south of its jōdan-no-ma. The main house of the Rikyūdō Sakai family in Nagano City places the principal reception room at the centre of the upper end with an irigawa front and back.
On site, look for an additional corridor-like strip between the reception room and the outer veranda or windows. Whether it is tatami or boards and whether it is one or two bays wide can be checked against the record.
References
- 犬山城天守｜文化遺産オンライン
- https://bunka.nii.ac.jp/heritages/detail/200169
- 旧相川家住宅主屋｜国指定文化財等データベース（文化庁）
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00015406
- 利久堂酒井家住宅主屋｜国指定文化財等データベース（文化庁）
- https://kunishitei.bunka.go.jp/heritage/detail/101/00002541
Last verified: 2026.09.27