The International House of Japan(I-House) was designed by three architects of Junzo Sakakura, Kunio Mayekawa, Junzo Yoshimura in 1955. The I-House was planned on the premises of Old Iwasaki Koyata House. At the Iwasaki Koyata House, the upper part was burned down due to air raids.

It is said that the proposal of three architects was a competition in December 1952, but it is thought that it was a proposal to decide a draft of collaborative design. A cooperation design began in early 1953, and the detailed design of I-House was completed in December. It is guessed that the staff members of three architects drew the part which the architect is good at each. The staff members of Kunio Mayekawa drew a frame of the building, the staff members of Junzo Sakakura described internal common space, and the staff members of Junzo Yoshimura drew guest rooms.

The I-House won the Japan Architectural Institute Award in 1956. The following values are confirmed from the evaluation of the Architectural Institute of Japan Award and architectural magazines of the time.

1. Work of high completeness by collaborative design.

2. Using the new construction method at the time。

Precast concrete and the like are utilized. Kunio Mayekawa and Junzo Sakakura who were already designing large scale projects are thought to be a new construction method.

3. A unique and harmonious Japanese-style beautiful expression

Using precast concrete and trees, it became a Japanese beautiful expression. Junzo Yoshimura used wood for the parts touched by hand, Kunio Mayekawa designed a wooden sash. It is mainly thought that these two architects intended.

4. The I-House block plan succeeded the garden of Iwasaki residence

Three architects respected the gardens of the Iwasaki residence from the original proposa.

5. Functional, sequenced space

It is thought that the functional and sequenced space was intended by Junzo Sakakura who was in charge of designing common space.

6. Pillar position and auditorium shell structure

The first plan of Sakakura Junzo had pillars inside the outer wall. Fugaku Yokoyama who cooperated with Mayekawa Kunio designed the structure of the roof of the shell structure of the auditorium.

7. The roof garden of the lawn which is continuous in the garden of Iwasaki residence.

Mayekawa Kunio already had a record in the roof garden.

The following conclusions are considered from the history of collaborative design and from many publication magazines at completion. Among the values of the above seven international cultural halls, 1) 3) 4) was intended by all three architects. 2) and 6) were intended by Kunio Mayekawa and Junzo Sakakura. 3) Tree use was intended by Kunio Mayekawa and Junzo Yoshimura. 5) was mainly intended by Junzo Sakakura. 7) was intended by Kunio Mayekawa.