The Seoul bureau chief of the Sankei Shimbun appeared before prosecutors for a second time Wednesday, for questioning about a controversial article about President Park Geun-hye.
The appearance of Tatsuya Kato, 48, at the Seoul Central District Prosecutors' Office followed another session of questioning on Monday, as prosecutors assess whether his article constitutes defamation and whether to bring criminal charges against him.
The office has imposed a travel ban on Kato.
A conservative civic organization filed a defamation suit against the newspaper's bureau on Aug. 9 over the article, which was carried in the Aug. 3 online edition of the newspaper.
The article cited rumors in the stock brokerage industry and in a South Korean newspaper that suggested Park, who is single, was not at the presidential office during a seven-hour period on the day of the Sewol ferry disaster in April, and may have been secretly meeting with a recently divorced former aide.
The presidential office has dismissed the rumors and the article as false.
Sankei Shimbun has said its report was filed mainly based on information contained in statements made in South Korea's National Assembly and a column published in a South Korean newspaper.
The case, which has drawn media attention, comes at a time when bilateral relations between Japan and South Korea have deteriorated due to a territorial dispute and historical issues.
It marks the first time a Japanese reporter has been questioned by South Korean prosecutors over reporting activities since 1993, when the bureau chief of Japan's Fuji Television was arrested on suspicion of receiving classified military intelligence from a South Korean naval intelligence officer. He was convicted and deported the following year.