Jacob Burridge, a teacher at Giralang Primary School, was on a two-month holiday in Japan with his wife Waka and daughter Matia. Just hours before his flight to come back to Australia on Tuesday, he was complaining of headaches and nausea.

Within five minutes he was unconscious.

After being rushed to a hospital in Kochi, Mr Burridge was put into an induced coma, with brain hemorrhages discovered on both sides of his brain.

The teacher was diagnosed with artery vascular malformation, a rare genetic condition affecting one in 3000 people with only a one per cent chance of rupturing.

Speaking to Fairfax from Japan, his brother Thomas Clifton said doctors initially told the family to brace for bad news.

"They told us to prepare for the worst and that he would be brain dead," he said.

"Signs are positive now. He moved his arm when his daughter asked him and is fighting the ventilator and kicking his leg."

While doctors have downgraded his condition from critical to critical-stable, Mr Burridge is still on life support, with the possibility of him being paralysed down his left side.

Mr Clifton said the family had been shocked by the news.

"My mum was hysterical. I was more in shock and knew I had to be the strong one and let the others do all the worrying and be frantic," he said.

After three hours of surgery on Friday, Mr Burridge will be back in the operating room for up to 20 hours on Monday.

"After that, if successful, they'll bring him our of the coma and start the rehab, and see how much damage was done," Mr Clifton said.

Since receiving the news about his brother's condition earlier this week and flying to Japan to support the family, Mr Clifton has set up a gofundme page to help with the large medical bills.

The page has already raised more than $59,000 in one day with many of the donations being made from members of the Giralang school community.

Mr Clifton said he had been blown away by the support.

"There's been a massive response, Waka is so grateful," he said.

"Jacob had many friends, and [with him] working at schools, so many people know him."

As well as being a teacher at Giralang, Mr Burridge also used to be a year 3 and Japanese teacher at Kaleen Primary School.

The gofundme page has set a target of $100,000, with hospital bills expected to be $1600 a day.

"We expect the bill will be over $200,000 before rehab," Mr Clifton said.

"We are all prepared to sell our houses and pay to rent at house in Kochi near the hospital for my mum to stay on."