Mountain & Opening by Eastern Design Office

The architecture is built on the slope of a hill with an elevation of 330 meters. The level difference  of the site is 8 meters.


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Architect: Eastern Design Office

Location:Takarazuka, Hyogo Prefecture, Japan

Client:American Club International Co, Ltd

Site Area:711.46㎡

Total Floor Area:361.84㎡

Structural Engineering:Hojo Structure Research Institute

Contractor:Fukasaka Co., Ltd

Photographer:Koichi Torimura

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This building is a design room for a Japanese sneaker brand, Dragon Beard, as well as a residential house. The site is located at Takarazuka-city, an exclusive residential district that commands an entire view of the Osaka Plain.

The architecture is built on the slope of a hill with an elevation of 330 meters. The level difference  of the site is 8 meters. By taking the advantage of the slope, the building is built based on two main design concepts as below:

  • To be underground in the warmth of the earth.
  • To fly like a bird.
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There is hard bedrock at 1.5 meters beneath the ground surface. The soil of the original topography slope is dug to allow the foundation to be raised on this bedrock. The excavated soil was then used to create the new mountain topography as shown in the red curving line. In other words, by heaping up the excavated soil,a new undulating mountainous topography is built. The lower floor is built under the mountain. The form which runs over the mountains is the upper floor. The corresponding upper and lower floors are made into one form.
The concept of enjoying the experience of gazing far into the distance, all alone in a spot on a grassy slope.

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Putting the ideas of a “slope” into order. The correlation between rising and falling(which means the up and down), crossing far and nearby nature. The multifarious worlds that people can sense in a place called “slope”.
A person standing, crouching or even flying off a slope. Only on a slope that people will be able to look back on the road they’ve climbed before and, also to be able to foresee the way they will go from now on. Therefore, the slope can be called a place that inspires people in a vision way.


To Be Underground In The Warmth Of The Earth

This design concept is dedicated to a lower floor, which is an invisible house (also known as residence or residential quarters)  in the mountain.

The height differences on site is 8 meter, which is higher than a two-story building in general. The lower floor is in the ground of the slanted site. It is invisible from the upper road. There is a hard bedrock layer at 1.5 meters beneath the ground surface.  The soil is dug until reaching the bedrock so that the foundation is supported by this bedrock. The soil dug is not wasted but being used to build two mounds that forms the new mountain topography. The residence that consists of living, dining, Japanese style room, bedroom and stockroom is inserted between these two mounds while the upper floor floating on these two mounds is a design room. An exclusive residential area on a hill features a good commanding view as its sales point. By building on this new mountain topography, all parts of the building especially those of the lower floor are close to the earth (or soil).  The mountains are designed to emphasize the slope.



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The surface of the two mounds is a type of raw material made from crushed marble called “Kansui”.  The glittering fragments of crushed marble on a whity surface make it shines brilliantly. This helps to create two visual white mountains. One of  the white mountains functions as a structural support for this building, while the other mountain conceals the bathroom at the lower floor (also known as basement). These two mountains are also set into the interior living spaces of the residential quarters.

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To Fly Like A Bird

This design concept is dedicated to a design room at the upper floor.

From here, one can enjoy the view of the Gulf of Osaka, high-rise buildings, Kobe port, Kansai Airport, Itami Airport, and shadowy blue mountains. As mentioned above, the land originally slanted at an angle of 18 degrees.
Mounds are built there to let the slope undulate where it helps to create the new waves from this new mountain topography. The upper floor was indeed designed to float on these mountain waves. In fact, the form is designed to pass over the new mountain waves.

In order to achieve this design concept, its architecture is designed to be like a voyage setting out with an 18 meter-long terrace. With this design approach, one can observe the sea and a range of mountains 60 kilometers away while the rows of other houses in this area are out of sight when standing on this terrace. In this case, the design of its opening also plays an important role. In short, you will sense that your body is slightly floating when you enter the building. It is the architect’s intention to give a sense of being on a deck of ships, but not in the house. The design room on the upper floor is design to be an architecture ship.

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The Plan

The plan is designed in L-shape. The edge protruding greatly from the slope is an opening that swallows the outside, with its straight eaves run amidst the curvilinear forms of the topography. The eaves project in a powerful manner not to be beaten by the inherent force of the topography. They are thin, thick, short, long and carved.

The architect’s design intention is to make one feel protected by the house, yet at the same time have the feeling of flying away. This is in fact making the two extreme concepts into one. The architect achieved this design challenge by corresponding the forms of the upper and lower floors.

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Basement Plan:
The lower floor is inserted between the two mounds.


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Site Plan & 1st Floor Plan:
The upper floor is designed to float on the mountain waves. In fact, the form is designed to pass over the new mountain waves. The design room act as a deck.



The Challenging Design Concepts In This Project

  • It is a cave and also a nautical form.
  • It is flying away, yet it is anchored.
  • It is drifting, yet it is homely.
  • It is sky, and it is Earth.
  • It is far, yet it is near.


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The Structure Of The Deck

The framework of the upper floor is of steel and the lower floor is of reinforced concrete. The upper floor evokes a sense of being on the deck of a boat and in order to achieve this feeling, the architectural columns and walls are designed as to make one unaware of their existence. When entering the house from the northern road, a 14meter wide opening and the 16.5 meter x3 meter terrace outside create the feeling that your own body is floating in the scenery. This is a deck.

To achieve this, the architect used two different methods:

1. Revaluation of the trusses

  • It is not immediately apparent; however, since horizontal slits were cut into the northern wall, trusses were set into it. It is like the structure of a bridge. Bridges are set into the upper part of the horizontal slits which allow the floor to float in the air while concealing the structural device.

2. Concealing the structural members in the curves

  • Columns are in the curves forming the openings and this also is concealed. The curves of the openings respond each other with the curves of the mountains. A fantasy is thus created by the repeated curves appearing over and over again.

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Living Space + Opening + Mountain

The lower floor fully utilizes the slope of the mountain. The hidden areas become mountains while the areas that is required light become valleys.  These rolling undulations are all part of the design.

Two Horizontal Eaves

The upper and lower floors are used in different ways. The upper floor is a design room while the lower floor houses residential quarters with some public spaces. As the demand of how the spaces should be is different,  the structure is therefore also different. In order to unify the upper and lower portions of the building, the curves of the mountain are made continuous with the curves of the openings.

There are two thin iron plate eaves on the openings, one with the length of 14 meters on the upper floor and the other with 16.5 meters on the lower floor. The thickness of the iron plate is only 9mm. The straight line of these two eaves emphasizes the expansive spreading horizontal width of this house. Consequently, this makes you forget that the house is on a sloped site.

Blue And White

The overall whiteness is not just a general white coat of paint. It is in fact white mixed with blue. This is because the architect wants the white color that corresponds with the blue sky. In addition, the architect intends this white to reflect the light of fragments of marble scattered in the raw material which covers on the surface of two newly built mountains.


According to the architect, this is a slope when architecture is erased. The architecture of the “house” is a “mountain.” The plan for this slope is to shape the mountain structurally, but that goal was to let people feel
the uninterrupted flow of the curves that define the mountain and to let the people have a sense of closeness to this wave-like mountain. A small change to the curve will lead to a loss of balance, affecting the way openings should be designed, the mountain, and the entire architecture will also have to change its form. However at this moment not even one person felt unnatural when standing on this undulating slop.




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