"We thought the restraint was inhumane and unnecessary in Kelly's case, but we had no idea it could cause Kelly's cardiac arrest," Pat Savage told a Tokyo news conference.
He said he was not considering taking legal action against the hospital, but the campaigners nonetheless urged a change in practice.
The number of hospitalised psychiatric patients that are put under physical restraint in Japan totalled 10,682 as of June 30, 2014, the latest date for which data is available, a twofold rise from a decade ago, according to the Health Ministry.
During the same period, the number of overall hospitalised psychiatric patients fell 11 per cent to 290,406.
Among those who are put under restraint, the duration of restraint averaged 96 days, Toshio Hasegawa, professor at Kyorin University told the same news conference.
This compares with several hours to several tens of hours in many other countries, said Hasegawa, who on Wednesday launched the group of psychiatric patients as well as professors and lawyers to raise awareness of such restraint and reduce the practice.
"What I would like to ask you first is to think about the feelings of those who are dying while under physical restraint," Hasegawa said.
- AAP