The tower has a floor space area of 379,408 square meters (4,083,910 sq ft), making it one of the largest buildings in the world by this measure.

While on a tour of Mori Tower on the morning of 26 March 2004, six-year-old Ryo Mizokawa was killed in a revolving door at the building's second-floor main entrance.

Mizokawa's head was crushed between the door rotating from his left and the outer frame; he died two hours after reaching the hospital.

This setting was changed to 135 centimeters (53 in), however, after the door began stopping unnecessarily when detecting a newly installed, nearby safety barrier.

After the incident, it was revealed that 32 people had previously sustained injuries caused by revolving doors at Roppongi Hills since the complex opened less than a year earlier.

Prosecutors argued that the Mori Building officials did not implement safety measures proposed after previous incidents because they would detract from the tower's entrance appearance.

[20] The incident spawned nationwide inspections of Japanese elevators by both Nippon Otis and the Land, Infrastructure and Transport Ministry.