Tokyo Governor Koike Yuriko is projected to win her third term following Sunday's vote.
Koike addressed her supporters and cited various challenges Tokyo is facing, such as soaring prices and the falling birthrate. She has pledged to take action against the latter by expanding free childcare.
"Our challenge is how to proceed with digital transformation as industries have changed significantly," she said.
"Furthermore, the environment for women's empowerment is insufficient compared to other parts of the world," Koike said, adding, "We must raise up our efforts to keep improving Tokyo."
Vote counting is still underway. NHK's projection is based on exit polls and information collected before the election.
Exit polls showed Koike ahead of other candidates, including Ishimaru Shinji, former mayor of Akitakata City in western Japan's Hiroshima Prefecture, as well as former Upper House lawmaker Renho.
A former defense minister, 71-year-old Koike has served in both the Upper and Lower houses of Japan's Diet. She became Tokyo's first female governor in 2016.
During the campaign, Koike stressed the achievements of her two terms in the governor's seat.
Koike faced a record 55 rivals in the gubernatorial race.