It was an idea so simple a young child could understand it.

Mililani sophomore Alyssa Tobita is the reigning state champion in girls tennis because she does everything well. But she does one thing better than any other: She keeps the ball in play.

Tobita took up the game about a decade ago after taking lessons from Punahou boys coach Rusty Komori. Komori saw the potential right away, since she had the first lesson down before she walked on the court.

"I knew she was going to be good," Komori said. "She understood one thing from the beginning: ‘You have to hit the ball in to win.’ Not a lot of players understand that, but you could see she got it from an early age."

She won the state title by being a human backboard, returning every shot and frustrating opponents. But the counterpuncher knows that it won’t always be like that. She will have to adapt or give up any hope of becoming the first four-time state champion since Mililani’s Erin Hoe in 1997-2000.

"I am not as strong as the other girls, so I have to work," Tobita said. "I think it will change — as you get older it is harder to play all defense and win because the shots come faster. I am going to have to develop my aggressive game a lot more."

Matching Hoe will not be easy. According to tennisrecruiting.net, Hawaii has five players rated with four stars or above. Tobita is one of them, and the rest are underclassmen who will challenge her for the next three years.

Tobita won the state title as a freshman last year with a victory over Waiakea’s Sarah Dvorak, the state’s only five-star recruit.

It is easy to say the OIA champion came out of nowhere, entering her first state tournament as a fifth seed despite her reign atop the state’s biggest high school league. Even Tobita didn’t give herself much of a shot. In order to get to Dvorak, she had to beat ‘Iolani’s Bobbi Oshiro, a personal friend who was seeded second, and fourth seed Kristin Poei of ‘Iolani.

‘When the draw came out, I thought (Dvorak) was going to win, too," Tobita said "I played her a lot in juniors. Tournament people all knew that whoever was better that day was going to win. But the draw was like ‘oh my gosh.’ "

Tobita will play in the Spring Junior National Championships this weekend at Central Oahu Regional Park, taking a break from dominating OIA play to test her game against the state’s best. Dvorak is the top seed in a bracket that contains Tobita, Punahou’s Scout Shutter and Dani Young, as well as Lani Rae Green of Waimea.

Tobita’s first singles match is Saturday at 8 a.m. against either Green or Katherine Lee of Punahou. She has a doubles match with Punahou freshman Ashley Ishimura against Shutter and Green on Friday at 6:30 p.m.

Few OIA players take part in elite tournaments, making it Tobita against the world. Mililani, which has won the OIA four straight years, travels to Waialua for a match on Wednesday. There will be no ranking points involved, but it will be fun nonetheless.

"I am OIA all the way," Tobita said. "I really enjoy the team part; just the support from everybody is motivation. I really like my high school team. I wish more OIA girls would play tournaments."

Since they don’t, Tobita will be a heavy favorite to repeat as OIA champion. One thing is for sure: She won’t give it up without a fight.

"She’s relentless," Mililani coach Jason Agsalda said. "She has such a will to win and so determined, she likes to practice. She is everything you want in a kid."