The patrol vessel Hakuo Maru is being dubbed the "phantom" or "death" ship by Chinese and South Korean fishermen for its tendency to suddenly appear when they are violating Japan's territorial waters.

The Fisheries Agency vessel patrols from the coast of Kyushu to Japan's border in the East China Sea. But the locations of the Japanese, Chinese and South Korean fishing zones are complicated, and trouble between fishing vessels and with illegal fishermen frequently occurs.

In particular, Chinese fishing boats have reportedly been crossing into Japanese waters recently because of a sharp drop in catches.