According to the Yokohama-based 3rd Regional Coast Guard Headquarters, it had received a report by radio from a crew at ~1 PM (Tokyo time). that the ship's crew were trying to extinguish the fire. The ship was without passengers and injuries were not reported.
The NYK Cruises' parent company NYK LINE said the fire had broken out on the top deck used to store materials and smoke had been visible as the city's fire department had joined efforts to put out the blaze, which had been extinguished at 4:15 PM.
MS Asuka II is anchored at Osanbashi Pier since April 1, 2020, following the Coronavirus (COVID-19) outbreak.
Asuka II has been in service since February 2006. She is 241 metres long and weighs around 50,000 tons. The vessel has max passenger capacity 960 (plus 150 staff-crew).
For more Asuka II accidents and incidents see at the ship's CruiseMinus page.