The immense upper deck is a rolling landscape of timber and grass designed as a new public space for Tokyo. This roof then folds back into itself. The principal of the folded plate has an amazing coherence, with the public realm twisting from outside to inside to form ramps in the internal areas. This puts the arrival and departure hall (pictured at right) in darkness at much of the day. This fundamentally humanizes the architecture. The origami ceiling skin coupled with strategic lighting is able to bring the space to life especially during times of darkness. The dark curves of the arrival and departure hall present a dramatic contrast to the sunlit curves of the roofscape above.
The diagrams at right show the arrival and departure hall at three different stages of the day. The first stage is approximately 6 am when the hall actually experiences the most natural illumination. (The time is meant to represent a time an hour or so past sunrise, which changes with the seasons) The second diagram shows the hall during the noon hour when the sun is at it's peak in the sky and the hall becomes a 'bat cave.' The final stage represents a time following sunset where the hall is, of course, dark and one can begin to see the effect of the lights on the origami ceiling structure.