Japanese scientists discover that mouse sperm held on the International Space Station for 9 months is able to produce healthy mice.
- AP via ''The New York Times
- Japanese Prime Minister Shinzo Abe is expected to dissolve the House of Representatives on September 28, 2017 to make way for fresh elections.
- A North Korean missile flies over Hokkaido, Japan, triggering the J-Alert system, following a similar event on 29 August.
- Japan agrees to help with the construction of an Indian bullet train.
- North Korea fires a Hwasong-12 ballistic missile which flies 2,700 km, passing over Hokkaido, northern Japan, prompting the activation of the nationwide J-Alert warning system. This is first time since 2009 that a North Korean missile has passed over Japanese territory.
- The death toll from flooding on the southern Japanese island of Kyushu rises to 15, with six others missing.
- Severe flooding on the Japanese island of Kyushu has caused seven deaths with twenty people unaccounted for.
- North Korea test-launches what is presumed to be its first intercontinental ballistic missile 933 kilometers into the Sea of Japan within Japan's Exclusive Economic Zone. An American expert theorizes the ICBM, which reached an altitude of 2,802 km, could potentially reach the U.S. state of Alaska.
- North Korea launches an intercontinental ballistic missile that flies 620 miles horizontally in about 45 minutes, landing in the Sea of Japan, according to Japan, South Korea and the United States.
- The death toll from recent torrential rain and flooding in Kyushu in southern Japan rises to 25.
- The National Diet of Japan passes legislation allowing Emperor Akihito to abdicate. The abdication is to take place within three years.