Whirling their batons expertly as they weave among the drums, the performers beat out a rhythm that builds steadily in a flawlessly syncopated rhythm. The Japanese-drumming piece, meant to recall the power of waves crashing into the coast, conveys an eerie power in the wake of the March 11 tsunami.

But when the members of Oto-Wa Taiko perform it, as they did on Sunday at a downtown fundraiser, there is an added sense of urgency: They are not just playing for an audience; they are playing for their brothers in faraway Sendai, where years ago, they forged close ties with another drumming group, Kamo Tsunamura Daiko.

Just three years ago, the two groups performed together at the Canadian Museum of Civilization — again on Mother’s Day — to commemorate the 80th anniversary of Canadian-Japanese diplomatic relations. And in 2009, the Ottawa group travelled to Sendai to perform with the Kamo Tsunamura Daiko. The two even have cut a CD together, titled Two Cities — One Beat.

Now they pray their performances, such as the one they gave Sunday at De La Salle High School, will help their friends in Sendai, one of the worst-struck areas of Japan.

It all started in 2001, when a teacher at De La Salle, Eric Beevis, travelled to Sendai to teach English.

“When I went there, I had no notion at all of playing drums,” he recalls, taking a short break at intermission from Sunday’s show. He had graduated from teachers’ college the year before and was just looking for a little travel and adventure before settling into his new career.

“I taught for a year, then I thought, ‘Why not broaden my horizons?’” He applied to work as a teacher’s assistant, and wound up in the town of Sendai.

At a festival during his first year there, the school invited him to join in a performance of taiko, a traditional form of Japanese drumming.

Then he was hooked: For the next two years he took lessons with Kamo Tsunamura Daiko; when he returned to Ottawa in 2004, he joined the Oto-Wa Taiko group; through Beevis, the groups soon forged close ties, culminating in their joint performances in 2008 and 2009.

News of the catastrophe left the Ottawa group reeling in shock: “There were lots of e-mails going back and forth,” says Beevis. Luckily, he adds, “all the members (of the Sendai group) were accounted for.”

Sendai was like a second home to him, he says: “It was hard to see places on the news that I know so well, looking unrecognizable.”

Aki Watanabi say the group chose Sunday for their fundraising concert in part to commemorate their first joint performance with the Sendai group, which also fell on Mother’s Day.

“It is meaningful for all of us, especially Eric,” he says.

One of the pieces in the show, Sendai Suzume Odori (Sparrow Dance) is a folk dance from Sendai; another, called Kyoten (Boom into the Sky), was composed by the Sendai group.

Watanabi co-founded the Ottawa group in 1989. The name “oto” means “sound,” and “wa” means harmony; together, the name signals not only the group’s hometown, but also the harmony its players need to establish among themselves and with their instruments.

The style of drumming is “stage-oriented,” says Watanabi: Performers don’t just sit in front of their drums; they also dance, and wield their batons dramatically. In some of the numbers in Sunday’s show, they wove in and out among several large drums, never once missing a beat in the many complex variations.

It takes several years to master taiko, says Watanabi; players practise three hours a week, although the Ottawa group also does a lot of performances — as many as once a week in the summer.

Hitomi Suzuta of the Ottawa Japanese Community Association says Sunday’s show was the last in a series of concerts and other fundraising events in recent weeks.

“We have all been very overwhelmed with the response in Ottawa and from Canadians in general,” she said. “People want to help in any way they can.”

She hopes people will continue to help as Japan struggles to rebuild after the catastrophe. “It took $185 billion and 10 years to rebuild after the Kobe earthquake in 1995, and it was much smaller than this one,” she notes.

Upcoming events include a film night at Library and Archives Canada on May 10 and a gala at the Canadian Museum of Civilization June 3.

To donate for earthquake relief, contact the Canadian Red Cross or call 1-800-418-1111