When sweethearts Erik Leong and Christi Yoshida decided to set the date, they weren’t planning their wedding. They were scheduling a different life-changing event: a kidney transplant.

Yoshida, who was diagnosed with diabetes in 2008, was on a fast track to renal failure and worse, and her fiance was going to give her one of his kidneys. That Leong, 30, turned out to be a near-perfect match for her organ transplant was unexpected.

“They said it was a freaky close match. I joked with him about it: ‘Are you sure we’re not related?’” laughed Yoshida, 29.

The transplant was done Nov. 2 by a team from the Queen’s Medical Center. Theirs was one of 51 kidney transplants performed in the state last year. Of those, only eight involved a living donor, according to the United Network for Organ Sharing, which is contracted by the U.S. Department of Health and Human Services to manage the nation’s organ procurement and transplantation network.

Leong is now back at work as a restaurant chef while Yoshida is focusing on regaining her full health and adapting to a new routine that includes taking a slew of medications four times a day. Their ordeal has been an extraordinary test of their compatibility.

“Erik is really my best friend and my other half — literally, too,” said Yoshida.

The two have known each other since grade school but didn’t start dating until 2013. By then Yoshida had already been dealing with serious complications from diabetes, a chronic disease that targets the kidneys, which play a vital role in removing excess fluid, waste and minerals from the body and helping regulate blood pressure and electrolyte levels.

As her kidneys declined at a precipitous rate, one of her doctors told Yoshida she would likely die at a young age.

“It was depressing,” she said. “I’d often come home crying.”

By 2010 Yoshida’s kidneys were functioning at only 25 percent, and two years later at below 10 percent. In February 2015 she took a turn for the worse.

“I couldn’t get through a day without throwing everything up in the bathroom at work. I wound up in the ER again,” said Yoshida, who was working at a security systems company.

She began hemodialysis, a tedious but life-extending treatment in which patients with advanced kidney failure are hooked up to a dialyzer, a machine that acts as an artificial kidney by filtering the blood a few ounces at a time to remove impurities and excess fluid. Yoshida required the exhausting treatments three times a week, up to four hours per session.

“Getting used to dialysis was a challenge,” she said. “I think the first time that I went to dialysis, they removed about 10 pounds of fluid from my body.”

Her doctors recommended a kidney transplant. Without a living donor, though, Yoshida was looking at a two- to six-year wait for a kidney, and it was doubtful she would live that long.

Kidney transplants from a healthy, living donor have far better outcomes since the surgery can be scheduled so that the organ is transplanted immediately from the donor instead of being kept on ice for hours before a transplant can be arranged, according to Dr. Alan Cheung of the Transplant Center at Queen’s Medical Center.

The most common living-donor transplants involve relatives, and siblings are usually the best matches, said Cheung, who performed Yoshida’s transplant. “Generally for genetically related donors there’s a better chance for a match,” he said.

But screening tests and other factors eliminated Yoshida’s immediate family as donors. Leong said he knew what he had to do.

“It was more like a joke at first,” he said. “Her mom them tried but they weren’t a good match. So I thought, ‘All right, what have I got to lose?’ Then every time I passed one of the steps, we were like, ‘Ha, ha, ha, that’s funny.’”

They were thrilled — and a bit stunned — when Leong was found to be a near-perfect match. “They said it was a superclose match, which is very rare,” Yoshida said.

The couple decided to schedule the transplant for later in the year when it would be more convenient for Leong to take time off from his job as chef d’ cuisine at Kaimuki Superette. In the meantime Yoshida continued dialysis, with Leong shuttling her from their Waikiki apartment to her appointments.

As the transplant surgery drew nearer, they grew more anxious.

“We’d talked about the surgery a lot before, but the closer it got, the more real it became,” said Yoshida. “It was a weird feeling because we were both happy and excited for a brighter future. The transplant was a good thing, but we were also nervous, being that a kidney transplant isn’t a minor surgery.”

So on Oct. 24 — there’s no forgetting the date — Leong tried to reassure Yoshida, asking her to identify something positive she could look forward to after the transplant.

“After thinking for a second, I replied that I was excited that I was going to have a healthier life, for things to be a bit more normal for us,” she said. “I hated being so sick all the time. I would like to think we could enjoy doing more things without worrying about my health so much.”

Leong had something else in mind. He told his girlfriend to close her eyes and then kissed her forehead.

“I opened my eyes because I thought he was being sweet to me to make me feel better,” Yoshida said. “Then he told me to close my eyes again.

“When he told me to open my eyes, he was in front of me on one knee — with a ring!”

Her answer to his proposal was, of course, “Yes.”

Their kidney transplant took place nine days later. Yoshida remembers crying as she watched her fiance get wheeled into the operating room first; it would be her turn a couple of hours later. They didn’t see each other again for three days, when Leong was able to walk from his room on the same floor at the Queen’s Medical Center to hers.

He was discharged from the hospital soon after that, and Yoshida stayed for several more days.

TYPICAL of many organ transplant recipients, Yoshida said she felt overwhelmed at first not only with gratitude “for Erik’s sacrifice” and the successful surgery, but for what lay ahead: a strict regimen of medications, doctor’s visits and dietary and lifestyle restrictions, such as avoiding crowds to reduce the risk of infection since her immune system was being suppressed by medication to prevent rejection of her new kidney. (In fact, Yoshida was re-admitted to the hospital last month to battle an infection and just returned home last week.)

The restrictions include no raw or undercooked food, which could be a problem when you’re engaged to a professional chef.

“I just feel bad for her because she likes her steak rarer than I do,” Leong said. “And no over-easy eggs; everything has to be well cooked.

“But it’s worth it for her to be healthy.”

Leong and Yoshida are a near-perfect match in many other respects: They enjoy anime and manga, going to the movies and, in healthier times, working out together and lifting weights at the gym.

And they have a thing for tattoos. Both are covered in an assortment of inked art, each design providing insight into their personalities and interests. A juggling court jester on Leong’s right calf reflects his irreverent sense of humor (and juggling skills!); the Disney character Stitch on Yoshida’s right calf is an apt representation of her feisty spirit.

“We take care of each other, we work as a team,” she said. “I think that both of us are relatively strong people that don’t like to show our weak moments. But with Erik I know that it’s OK to have my weak moments and be human. Even when I don’t want to show it, he’s pretty good at reading me. And it’s the same thing the other way around.

“He always knows how to cheer me up when I’m feeling down.”

Another plus: He’s a chef.

“He’s the first guy that I don’t worry about when I’m sick that I’ll only be eating canned soup.”

Leong returned to work at Kaimuki Superette at the end of November and is now helping restaurateur Ed Kenney and executive chef Sean Priester open Mahina & Sun’s at the new Surfjack Hotel & Swim Club on Lewers Street in Waikiki.

It will take six months or longer for Yoshida to fully recover. She’s already been cleared to work and hopes to find an office job. (She’s a certified wedding planner.)

The couple admitted they’re struggling financially since Yoshida was unable to work while on dialysis. They haven’t set a date for their wedding, saying their first priority is to save money.

“Weddings cost money!” Yoshida said.

“We don’t have our hearts set on any real big details yet, but we talk about it all the time,” she added.

One detail they have settled on: “We’re definitely going to Disneyland for our honeymoon.”