The record, step by step
This site's electronic-timing era opens at the 1968 Mexico City Olympics. There Jim Hines became the first man under 10 seconds (9.95), and at the same Games Wyomia Tyus ran 11.07 for the women. The men's record later passed through Carl Lewis and Maurice Greene before Usain Bolt reached 9.58 at the 2009 Berlin World Championships — a mark that still stands.
The women's world record is Florence Griffith-Joyner's 10.49 from 1988, which has also stood for a long time.
Japan's progression
Japan's record begins with Hideo Iijima's 10.34 in 1968, and for decades the 10-second barrier was the target. Koji Ito ran exactly 10.00 in 1998, and in 2017 Yoshihide Kiryu broke through with 9.98 — the first Japanese sprinter under ten seconds. Abdul Hakim Sani Brown and Ryota Yamagata followed, and the record now stands at Yamagata's 9.95 (2021), matching the time of the old men's world record.
The women's record is Chisato Fukushima's 11.21 from 2010.