The stadium, positioned as the central facility of Oita Prefectural Sports Park, is an impressive structure. It has a clear-cut shape that looks like a part of a sphere cut off and placed on the ground. An oval opening in the central part of the roof creates a beautiful curve, which cuts off a part of the rounded roof that tends to look monotonous. What's more, this oval opening can be closed with a retractable Teflon^® membrane roof. Taking in natural sunlight through the opening on top, and fresh air through the opening at the circumference of the roof between the ground and the roof, the stadium enclosing the grass-covered ground creates a "second nature" inside.

This stadium is designed to be a multipurpose facility for a variety of applications, ranging from World Cup soccer games and track and field events of the National Athletic Meetings, to cultural events and large-scale pop music concerts. The architect's solution to these various applications is a "sphere," a shape that cannot be any simpler. The retractable mechanism of the roofs is so simple and clear that the fabric roofs of the same spherical shape as the dome slide over the dome to close the opening. As its nickname "Big Eye Stadium" suggests, the membrane roofs that close the oval opening from both sides are just like huge eyelids. If you see the closed roof from outside, it looks like a contact lens attached to a huge eyeball. It owes much to its basic concept of "spherical shape." The retractable roof, including the frame system, is so thin that it is easily integrated with the fixed portion of the structure. At the same time, Teflon fabric and the technology to fabricate it to a membrane structure are indispensable. The lightweight membrane roof with high weatherability and tensile strength -- as well as translucency -- made the integrated retractable roof possible by having a shell shape of a cut-sphere.

The oval opening in the ball-shaped dome has a circular plane, and an elliptical stadium lies underneath. Goals are placed on both ends of the pitch. It is like coming down from the sky to a field of bipolar rectangular ground. The structure's spine is in the major axis direction and the ribs are in the minor axis direction. A movable camera can slide along the spine of trussed beam in the major axis direction to follow the game. The spine is oriented in the north and south direction, and the oval opening is deeply cut in the same direction. The shape of the opening offers the required sunlight to the grass.

The retractable roofs are closed right above the spine, after gradually moving parallel up to the spine. They are pulled up with wires that have a winch member at the bottom. However, each rib has a different curve ratio from the others, and each wire has a different load from the others. Moreover, they are huge. The giant's blink is supported by advanced technology that calculates and controls the loads, and by external wires powered by computers. Because the opening is so huge, there may not be comparable data; however, this simple form of the opening must help save costs.

According to the plan view, an elliptical arena is placed in the circle of the whole shape, and other facilities are arranged in the space between these two different shapes. This method is very simple -- in a sense, a general solution -- and is also applied to Toyota Stadium, designed by the same architect. However, even setting aside the differences of size and design conditions, the two stadiums have entirely different styles. Not only that, but the messages sent by the structures also differ, which is very interesting. Toyota Stadium underscores the cultural aspect of sports, whereas this stadium seems to send more of the architect's view of nature and the world. Whether it is a theater or a sports stadium, we experience condensed time and a different world there, apart from the daily life. In the excitement of a play, a sports game, a concert, etc., we move to another world for a moment. For those who go to a theater or a stadium expecting it to be a memorable experience, there is nothing more disappointing than a boring game or a dull show.

The big difference between Oita Sports Stadium and other similar facilities is that this stadium gives an impression that a part of the world is cut off and placed there to create a unique universe.

I do not know whether the impression of a universe comes from the spherical shape or the contrast between the structure and the environment. The architect indicated that a combination of simple geometric forms leads to limitless creation of forms, comparing it to the combinations of alphabets to create the vast world of literature. It reminds me of reading a literature that Western space magazines seeking a "wise man's stone" would find their way to an infinite world's view created by combinations of words.

It might be just coincidence but we have a pineal gland in the brain that is said to be a degenerated eyelike organ. It seems that we had a third eye in our brain to look up to the sky, rather than two eyes to see the world on the earth. Since people abandoned the universe to stay on the earth, the third eye became useless and degenerated. Seeing the Big Eye watching only the sky, such a thought came to my mind.