The Japanese delegation is tasked with gathering information on the results of the high-level meeting, and holding consultations with US diplomats, the Kyodo news agency reported.
The delegation reportedly includes Shotaro Yachi, the head of the Japanese National Security Council. The agency suggested that in Singapore, Yachi might hold a meeting with Trump’s national security adviser John Bolton.
Both Kim and Trump arrived in Singapore earlier on Sunday.
READ MORE: Trump Arrives in Singapore for Talks With North Korea's Kim
After his arrival, Kim met with Singapore's Prime Minister Lee Hsien Loong. The two leaders shared a historic handshake in front of reporters before retreating to private quarters for one-on-one talks.
The talks between the US and North Korean leaders, which will be devoted to de-nuclearization of the Korean Peninsula, will be held at the Capella Hotel on Singapore's Sentosa Island on Tuesday.