Former Otaru Branch of Mitsui Bank
The Otaru Branch of Mitsui Bank was built in 1927 and operated until 2002. The building was restored and reopened as a museum in 2016. Visitors can see parts of the bank that were once off-limits to the public and learn about the development of the Ironai banking district from the early twentieth century, through exhibits in the open-plan banking hall.
In the basement is a walk-in vault with safety deposit boxes for customers. It is surrounded by a tiled corridor with a channel to drain the condensation which formed on the cool basement walls in summer.
The building was designed by architect Sone Tatsuzo (1853–1937) in the Italian Renaissance Revival style, inspired by the opulent merchant buildings of fourteenth- and fifteenth-century Italy. Sone designed the building with a steel frame and reinforced concrete structure, based on lessons learned from the Great Kanto Earthquake of 1923.
The Otaru branch was a symbol of the city’s financial vigor in the early twentieth century when Mitsui was one of twenty-five banks in Otaru. Sone was a classmate of Tatsuno Kingo (1854–1919), who designed the Bank of Japan Otaru Branch in 1912. The Mitsui Bank Otaru Branch building is part of Otaru Art Base, five historical structures that are open to the public as museums and art galleries.