Old calculations using anime scenes, I think it's too dangerous
Saiki shows a school close to Skytree that can be seen, use the Sumida district as a starting point. Saiki must be around there.
He took a short flight from Tokyo to Washington, D.C >> https://i.imgur.com/9R7mzcp.jpg
^^^^
Beginning with his flight and ending with Reita Toritsuka finished speaking, he reached the Pentagon.
Anime Time frame
Media:rightsecondharvestmouse.mp4
The moment he flew until the time Reita Toritsuka finished speaking is 1.30 to 4.74 or 3.44 s
Distance from Sumida (tokyo) to pendagon = 10,892 km (https://1th.me/qTSJd)
10,892 km / 3.44 s = 3166279.07 m/s
Mach 9304
Final Result[]
Kusuo Saiki flies to America = 0.01c (Sub Relativistic)