The area consumed by the fires reached 1,373 hectares (3,393 acres) as of early Sunday morning, up 7 percent from a day earlier, Reuters reported.
The fires threaten residential districts of Otsuchi on the Pacific Coast — a town that lost nearly a tenth of its population in one of Japan’s worst disasters, the March 2011 earthquake and tsunami.
Evacuation orders are in place for 1,541 households or 3,233 residents, roughly a third of Otsuchi’s population.
“Although the Self-Defense Forces are fighting the fires from the sky (with helicopters), the dry weather and winds are helping the fires expand,” Otsuchi Mayor Kozo Hirano told a press conference.
One Otsuchi resident said he worried about the damage the wildfire could inflict.
“A fire burns everything down. With a tsunami, you might have something left after the destruction,” Yoshinori Komatsu, 74, said as he watched Self-Defense Force helicopters dump water over fires in the distance.
The only casualty to date has been one minor injury suffered when a person fell at an evacuation center, Japan’s Fire and Disaster Management Agency said on its website.
No rain is expected in the region on Sunday or Monday, but a brief shower is forecast on Tuesday, according to the Japan Meteorological Agency.
The cause of the fires is unclear and under investigation.