The North Korean ferry Mangyongbong-92 arrived at Niigata port Tuesday morning for the first time this year.
The 9,672-ton ferry carried around two dozen passengers and about 50 tons of cargo. It last entered the Sea of Japan port in October.
Among those who gathered on the pier to protest the visit was Fumiko Hirano, 56, whose younger sister, Rumiko Masumoto, was apparently abducted from a Kagoshima Prefecture beach in 1979 along with Shuichi Ichikawa.
The ferry is suspected of being used for smuggling and illegal cash transfers, as well as transporting spies.
Its arrival comes as Sakie Yokota, whose daughter, Megumi, was abducted by North Korean agents at age 13 in 1977, is in Washington to testify at a congressional hearing on the abductions.
The Land, Infrastructure and Transport Ministry will carry out its first "port state control" safety inspection since September.
The ship will leave at 10 a.m. Wednesday.
The Mangyongbong-92 is scheduled to call at the port 18 times by the end of October.
