On the night of the fifteenth, two helicopters belonging to Yokota Air Base of the US Army made an emergency touchdown at Chofu Airfield in Chofu City, Tokyo. According to the Tokyo Metropolitan Government, no crew members had been injured and no engine bother was confirmed, so the airplane is scheduled to return to Yokota Air Base on the morning of the sixteenth.
Source
Two U.S. army helicopters make an emergency touchdown at Chofu Airport, 13 crew members injured | NHK
