Naka 12th Building No. 6 Newly Built
[Drawing by Ryoichi Kawamoto]

This article introduces the blueprints for Naka 12 Building No. 6, which was completed in 1920 (Taisho 9) (located in the middle of the north side of the current Marunouchi Park Building). From the stamps, we can see that Kawamoto Ryoichi was in charge of the architectural design and Yamashita Juro was in charge of Structural Engineering under Chief Engineer Sakurai Kotaro. Kawamoto graduated from what is now the University of Tokyo in 1914 (Taisho 3) and joined the Real Estate Department of Mitsubishi Limited Partnership Company. He was in charge of Mitsubishi Bank Head Office and Naka 12 Building No. 6, and later became involved with Maru Building. After the Great Kanto Earthquake, he changed jobs and became head of the architecture department of the Dojunkai, before going independent and working on Okuno Building (formerly the Ginza Apartments), Kudan Kaikan (formerly the Military Hall), Tamuracho Nissan Hall (no longer in existence), and others.
Now, let's take a look at the blueprint for Naka 12 Building No. 6. It has one basement floor and four aboveground floors, and is made of reinforced concrete. It has a very simple form, with two spans on the short side, wall columns on the perimeter, and round columns in the center. Although facade has a three-story structure, it has tall vertical windows spaced at equal intervals, and is geometric with little decoration. Looking at the plan, the number of tile rows in the vertical direction is indicated, just like in the brick construction era. The joint width is 12mm to 15mm, which is larger than the brick joint dimensions, and the joints are solid. The tiles on the basement are not uma (tiles arranged horizontally and half of them are offset and pasted alternately), but imo-bare (tile joints are pasted vertically and horizontally), and the columns between the windows are finished with imitation stone, with tiles only pasted on the protruding corners. In other words, it breaks away from the rules of tiles that developed from brick construction, and is used in a way that seems to say, "It's reinforced concrete, so we're free!" Looking at the Kudan Kaikan (1934), known for its Imperial Crown Style design, which he designed later in life, the facade tiles are freely used with protrusions and recesses on each step, the original roof tiles have a jagged shape, and the helmet-like decorations on the capitals of the columns are geometric and Gundam-like. Kawamoto's drawings for Naka 12th Building No. 6 are interesting as an early example of the advent of an era of free facade design using reinforced concrete and tiles.