Without elaborating, Japan on Friday briefly responded to an olive branch gesture by North Korea.
Tokyo is "paying attention," said Chief Cabinet Secretary Yoshimasa Hayashi, referring to the statement by Kim Yo Jong, sister of North Korean leader Kim Jong-un.
In a rare move, Kim said Thursday that the two countries can open up "a new future together.
Hayashi did not elaborate, citing a "possible negative impact on negotiations about the past abductions of Japanese nationals by Pyongyang," Tokyo-based Kyodo News reported.
Kim earlier said Pyongyang would be open to improving ties with Tokyo, even hinting at a possible future invitation to Pyongyang for the Japanese prime minister.
Her remarks came after Japanese Prime Minister Fumio Kishida last week said he felt a "strong need" to change the current relationship between the two longtime rivals.
In 2002, North Korea admitted that it had sent agents to abduct 13 Japanese people in the 1970s and 1980s, pressing them into service training its spies in Japanese language and customs.
Japan's former Prime Minister Junichiro Koizumi paid a landmark visit to Pyongyang in 2002, and met Kim's father Kim Jong-il.
His visit led to the return of five Japanese nationals and a follow-up trip by Koizumi, but the diplomacy soon broke down, following Tokyo's claim that Pyongyang was not coming clean about the abduction victims.
