Bill and Mary Owens had a choice: Save the home where they’d raised three children or save Cascos Martial Arts Academy, an East Oakland studio where they’ve trained thousands of students.

It really wasn’t much a choice at all.

At the tail end of the subprime mortgage crisis, when adjustable-rate mortgages left many homeowners susceptible to defaults and foreclosures, the Owenses chose to let their house go in 2012.

“We lost our house to stay here,” Mary Owens said, as she sat on a stack of folding mats in the MacArthur Boulevard studio they’ve owned for 45 years. “The camaraderie here — the parents, the children — they’re family.”

They were behind on mortgage payments for the house and the studio, and they reasoned that they could afford only the studio, which cost $6,000 per month, if they cut out the house payment, which leapt to more than $2,000 per month.

“If the balloon payment hadn’t hit, we probably would’ve been able to do it,” Bill Owens said of keeping both the studio and the house. “When the balloon payment came, we had to make a decision. If we let the school go and kept the house, where would we teach?”

The house they lost is around the corner from the studio, the first home you see on 73rd Avenue after making a right turn from MacArthur. The Owenses now live in an apartment in the building they also own next door to the studio.

On Saturday, there’s a reunion celebration for former Cascos students and friends at Geoffrey’s Inner Circle in downtown Oakland. Bill Owens will be honored for a half century of teaching.

But, to me, the event is really celebrating two people who’ve held on as the neighborhood around them has changed. Even as enrollment numbers have dipped significantly, they’ve kept their studio open for more than four decades because they want to give their students, who are mostly black, something to be proud of.

“He felt he really wanted to stay to support the community,” Mary Owens said.

“If I couldn’t control nothing else, I could control the kids that came through me,” Bill Owen, 74, added. “I could give them something to be proud of, to be proud of themselves. If I let (the studio) go and took a bus driving job, that would cheat the kids I wouldn’t get to reach.”

Bill Owens moved with his family from Texas to the Bay Area when he was 7. His family lived in San Francisco and Richmond before settling into Oakland. He graduated from Oakland Tech High School.

He got interested in fighting because of the Wednesday night fights at Bushrod Park in North Oakland. He’d climb trees to watch older boys from Berkeley and Oakland scuffle over girls after the weekly dances ended.

“I saw some real vicious fights,” he recalled. “I wasn’t in them. I was too little. I was considered one of the little kids. It made me aware of what you had to do, which means you had to know how to fight — or run.”

Bill Owens started seriously training in 1967. He developed his own technique called Blossom Fist, which is a blend of karate and kung fu and other fighting styles such as Brazilian capoeira.

The hand movements draw floral patterns in the air while defending and striking. It reminds me of the sweeping hand gestures of an orchestra conductor.

The Owenses met while working at the post office on Seventh Street in Oakland. Their schedules overlapped for a few hours so they’d chat in the break room.

“He was so different,” Mary Owen recalled.

She moved to Oakland from Paso Robles for the job. She didn’t like to go to parties. Instead, she read books, swam and hiked.

“He was such a gentleman,” Mary Owens, 68, said. “I really liked that. I started to go out with him.”

She started as his student in 1971, and they were married 12 years later.

In the studio they opened together in 1972, there’s a shelf of dusty trophies overlooking the floor, a reminder of the world-class skills of the owners. Mary Owens, still limping from left knee replacement earlier this year, has as many trophies as her husband.

On one wall, there’s a family tree with the names of more than 100 black belts the Owenses have trained, including their three sons.

As we talked, a young woman came into the studio with her sister. Bill Owens spent 20 minutes talking to the women, who said they walk past the studio daily. Cascos doesn’t get many walk-ins from the neighborhood these days.

In the ’80s and ’90s, Cascos thrived back when the neighborhood had a lot more black families. Back then, if you got to class late you might not have a place to stand, Bill Owens told me.

Today, enrollment is down to about 50 students per week. A precipitous decline began in March 2009 after a convicted felon fatally shot four Oakland police officers in a shooting spree that lasted just over two hours.

The first two officers were gunned down during a traffic stop in front of the studio while Bill Owens taught a class. Parents told him it wasn’t safe waiting for their children outside, so they pulled them from the school.

“The way the world is now, you need a parking lot,” Bill Owens said. “When I came along, parking wasn’t that essential. People could park two blocks up the street and it didn’t matter. But now, everybody is so concerned about the car, and, of course, they should be — break-ins and safety.”

He sighed.

“If you could move the same building into someplace like Hercules, Pinole, it would be booming,” he said.

Still, Bill and Mary Owens don’t plan on leaving East Oakland as long as they have students to uplift.

“It don’t matter what you’re dressed like or what your name is, you better know you’re the greatest person on Earth,” Bill Owens said. “There’s God and there’s you, and if you don’t believe that, I can’t teach you.”

San Francisco Chronicle columnist Otis R. Taylor Jr. appears Mondays, Wednesdays and Fridays. Email: otaylor@sfchronicle.com

Twitter: @otisrtaylorjr