The other day I wrote that Palaceside Building ranked No. 2 in "Japan's Top 10 Cool Office Buildings." That list naturally includes very tall buildings, and when I wrote "including Mode Gakuen's 50-floor super-high-rise," someone asked, "How many floors count as high-rise or super-high-rise?"
Conclusion: there seems to be no precise definition, but roughly "high-rise" is over 31 meters and "super-high-rise" is roughly 60–100 meters or more.
First, the Fire Service Act. Article 8-2 defines a "high-rise building" as one exceeding 31 meters — roughly equivalent to 10 stories or more. Thirty-one meters is thought to be the height a ladder truck can reach. The old Marunouchi Building, completed in February 1923 (Taisho 12), was 100 shaku = 31 meters; when the Imperial Palace outer area was designated a scenic zone in 1933 (Showa 8), eave height used Marubiru as the standard, and because Marubiru withstood the Great Kanto Earthquake half a year after completion, the Urban Buildings Act (predecessor of the Building Standards Act) limited building height to 31 m for seismic reasons — a limit that continued after the war.
So the definition of high-rise is relatively clear.
Super-high-rise, however, is vaguer. According to the "Architectural Dictionary" (Shokoku-sha), the term was coined for buildings far exceeding 31 meters when that height limit was lifted. The 31-meter cap was eased in 1963 (Showa 38) thanks to advances in building technology; Kasumigaseki Building (opened 1968, 36 floors, 147 meters) is considered a pioneer of "high-rise buildings"= photo upper shows it when newly completed; beyond the Imperial Palace to the right rear you can also see Palaceside Building's round towers(^―^). However, the first building after the limit was eased seems to have been Hotel New Otani (opened 1963, 17 floors, 72 meters), when "super-high-rise" may not yet have been a familiar word.
"Kojien" dictionary says a super-high-rise building is often defined as 15 stories or more, or 100 meters or more in height. At 4 meters per floor, 15 stories is 60 meters — so by this standard it is 60 meters or more, or 100 meters or more; quite broad.
Searching the Weblio online dictionary: "Buildings of 60 meters or more face different restrictions under the Building Standards Act, MLIT approval, the Aviation Act, the Fire Service Act, and so on — so buildings over 60 meters are often called super-high-rise" (from a Sanko Estate site). This seems to refer to Article 20 of the Building Standards Act, which imposes strict structural rules on "buildings exceeding 60 meters in height." Shinjuku Ward, with its cluster of super-high-rises, defines the target of its "Super-High-Rise Landscape Formation Guidelines" as "buildings exceeding 60 meters in height."
Searching The Mainichi Newspapers database (excluding regional editions) for "super-high-rise" returned 1,144 hits. The earliest is "Kasumigaseki Building completed" (April 13, 1968). After that the term appears often in articles, but definitions are not strict — for example, "If water shortages continue, super-high-rise city Tokyo in big trouble" (July 11, 1987) describes "34 super-high-rise buildings over 45 meters born in just one year amid the redevelopment rush called the 'first year of Tokyo transformation.'"
Now, Palaceside Building's nine-story section is about 37 meters high; the east and west white elevator towers are a little over 50 meters. By the 31-meter standard it qualifies as a "high-rise building." Hmm. With super-high-rises clustered nearby in Otemachi, I do not really feel "high-rise"... Well, never mind. I will not worry about it.