The MSDF's minesweeper Ukushima, carrying a crew of about 40, reported that the blaze broke out in the engine room at around 9:50 am local time, when it was sailing some 2.5 kilometers off Oshima island in Fukuoka Prefecture, Kyodo News reported, citing the local coast guard and fire department.
Ukushima's crew evacuated to another MSDF minesweeper Toyoshima by around 3:45 pm local time, but an engine room crewman, later identified as 33-year-old petty officer 3rd class Tatsunori Koga, has not been found yet, according to the coast guard and the MSDF.
Another crew member in his 20s who suffered a non-life-threatening injury was taken to hospital, the report said.
At the time of the fire, the two were on duty in the engine room, Xinhua news agency reported.
Toyoshima, which joined the coast guard in the fire-fighting and rescue operation, reported around 2 pm local time that the fire on Ukushima was contained, but a flare-up was confirmed later, it added.
Ukushima, which left the MSDF base in Shimonoseki, Yamaguchi Prefecture, earlier Sunday, was sailing to Kagoshima Prefecture and conducting a drill.