The building's height is 212 meters to the top of the roof, and 225 meters to the architectural top.
Its entrance lobby is on the second floor.

The X-shaped steel braces on the side of the building serve as seismic reinforcement and also as braces for the doors of the machine rooms at each end of every floor.
The doors are 4–5 floors tall, for replacement of equipment such as air-conditioners.
As in the older Keio Plaza Hotel, some fire escape exits are exposed outside the building to prevent smoke from accumulating in the case of fire.

In 2013, Mitsui Fudosan and Kajima Corporation began installing six massive pendulums on the roof of the building to counter long-period earthquake ground motion.
The pendulums will reduce magnitude of building motion by half or more during a major earthquake, such as the Great East Japan earthquake of 2011.
The building's height is 212 meters to the top of the roof, and 225 meters to the architectural top. Its entrance lobby is on the second floor. 
The X-shaped steel braces on the side of the building serve as seismic reinforcement and also as braces for the doors of the machine rooms at each end of every floor. The doors are 4–5 floors tall, for replacement of equipment such as air-conditioners. As in the older Keio Plaza Hotel, some fire escape exits are exposed outside the building to prevent smoke from accumulating in the case of fire.
In 2013, Mitsui Fudosan and Kajima Corporation began installing six massive pendulums on the roof of the building to counter long-period earthquake ground motion. The pendulums will reduce magnitude of building motion by half or more during a major earthquake, such as the Great East Japan earthquake of 2011.
Shinjuku Mitsui Building