Chief Cabinet Secretary Suga Yoshihide says the Japanese government continues to watch the situation in Hong Kong with grave concern.
Suga spoke to reporters on Tuesday after Hong Kong police arrested pro-democracy activists and a media tycoon under the territory's new national security law.
He called Hong Kong an extremely important partner for Japan, due to their close economic ties and exchanges between people.
Suga said Japan has consistently stressed the need for Hong Kong to maintain its free and open system and develop in a stable, democratic manner, under the "one country, two systems" framework.
He added that Japan has taken various opportunities to convey its position to China, including phone conversations between their foreign ministers.
Suga said the Japanese government will continue to work closely with relevant countries and respond appropriately.