Kath Tunnicliffe, previous patient of Mr Yuvraj Agrawal and who taught at The Wordsley School, near Dudley, won four gold personal gold medals, and two more as part of a relay team, at the event in the city of Fukuoka.
Kath won medals as the world's fastest woman aged 70-74 in the 200m backstroke, 100m backstroke, 50m freestyle, and 100m freestyle. As part of a mixed relay team in the combined 280-319 years age group, she won gold in the medley and freestyle events.
She also won silver in the 50m back crawl.
She also broke her own personal record as the fastest British woman in her age group in the 200m, finishing in three minutes, 26.2 seconds.
Kath, who lives in Holly Close, Kinver, said she never expected to do so well, particularly following her operation to treat arthritis.
"I didn't set myself any targets, I just thought I would do the best I could," she said.
"I just looked around, and saw that the others were all behind me, and thought 'I've won!'"
Kath worked at Wordsley School, previously Buckpool School, for 36 years, up until her retirement in 2014.