Eimi Koga, who led five Hawaii golfers into match play at the 63rd U.S. Junior Girls Championship, is the only one remaining after Wednesday’s first round.

The reigning state high school champion, who will be a junior at Moanalua, defeated Megan Blenien of Oklahoma, 3 and 2, at Olympia Fields (Ill.) Country Club. Koga trailed only once and took the lead for good when she won the 11th, 12th and 13th. She was seeded third after qualifying.

‘Iolani senior Marissa Chow drew medalist Ariya Jutanugarn and lost, 6 and 4. Chow birdied the first hole and held her lead for four holes. Jutanugarn, this year’s Rolex Girls Junior champion, tied the match with par on the fifth hole, then birdied six of the next nine to take control.

Katelyn Dambaugh, last year’s U.S. Girls’ Junior Amateur runner-up, defeated Maryknoll eighth-grader Mariel Galdiano, 5 and 4. Galdiano, 13, played in the U.S. Women’s Open two weeks ago. She never led in her opening match.

Allisen Corpuz and Kacie Komoto also lost. Corpuz, 13, fell to Alison Lee of California, 3 and 2. Komoto, 16, lost to Florida’s Kristine Odaiyar, 4 and 2

The tournament was played in a heat index of 110 degrees. The second and third rounds are today.

At the 64th U.S. Junior Amateur in Bremerton, Wash., Lahaina’s Aaron Kunitomo won his first-round match, 2 and 1, over Matthew Nesmith of South Carolina. Kunitomo took his first lead on the 11th and won four of the final nine.