A member of the Pana Wave Laboratory sect died at a hospital Friday, having been found unconscious in a creek here earlier in the morning, firefighters said.
The creek runs beside a building used by the sect.
The local fire department received a call around 1:50 a.m. from another member of the group who said he had heard a noise, looked into the creek and saw the man.
The dead man was identified as 50-year-old Hisao Kodama, believed to be from Oita Prefecture. The cause of death was not immediately known.
His head was bleeding when he was pulled from the water; investigators said he may have struck his head when he fell into the concrete-lined creek.
Last month, the Fukui Prefectural Police searched the group's headquarters in connection with the death of another member, 40-year-old Satoshi Chigusa, an assistant professor at the Fukuoka University of Education.
Chigusa's body was found with bruises on his back.
The group drew media attention earlier this year when some of its members, clad completely in white and traveling in a caravan of white vehicles, stopped along roads in central Japan.