A Japanese official has expressed discontent after South Korean plaintiffs launched actions to seize assets from two Japanese companies involved in Japan’s wartime forced labor of Koreans. 

According to Tokyo-based Kyodo News, Yasutoshi Nishimura, a deputy chief cabinet secretary, told a Japanese satellite broadcaster on Wednesday that it's “very regrettable” they made such attempts on “such a good day.” 

He was referring to Wednesday’s coronation of Crown Prince Naruhito as Japan’s new emperor, which ushered in the “Reiwa” imperial era. 

On the same day, Korean plaintiffs in the pending legal cases against Nachi-Fujikoshi and Nippon Steel filed a motion in South Korea seeking the selloff of the Japanese firms' seized assets. 

Nishimura said such actions constitute a violation of a 1965 normalization treaty between South Korea and Japan, adding Tokyo is demanding Seoul take specific measures to deal with them.    

The plaintiffs’ move follows the South Korean top court's decisions last year in favor of wartime forced labor victims and their families.

Tokyo reportedly lodged an official complaint through a diplomatic channel with the South Korean government.