Japan plans to invite Chinese Premier Li Keqiang for a formal visit coinciding with a trilateral summit with South Korea in May, indicating Tokyo’s eagerness to improve ties with Beijing, Japanese government sources said Friday. However the invitation to South Korean President Moon Jae-in for the summit is likely to be for an unofficial visit, possibly reflecting the chill in relations caused by a rekindled dispute over the so-called “comfort women”. It is Japan’s turn to host the trilateral summit, and it has suggested to China and South Korea that the long-delayed event take place in May, the sources said. And as years of tension between Japan and China begin to give way to a thaw, extending an invitation for a formal visit to Li is viewed as a step toward the goal of getting Chinese President Xi Jinping to make a state visit to Japan down the track. What to watch for at China’s Two Sessions The last Chinese leader to make an official visit to Japan was premier Wen Jiabao in May 2010. Li is expected to be invited as an official working guest, a step down from a state guest or official guest, but he is likely to have a meeting with Emperor Akihito included in his itinerary, according to the sources. Although improving recently, bilateral ties between Japan and China have been strained in recent years, particularly over the Senkaku Islands, called Diaoyu in China, which are uninhabited islets in the East China Sea controlled by Japan but claimed by China. China hardened its stance toward Japan after the Japanese government under Prime Minister Shinzo Abe’s predecessor Yoshihiko Noda bought most of the islands from a private Japanese owner in 2012. According to the sources, the Japanese government hopes to have Li visit the country for three days including a formal summit and dinner with Abe. Japan objects to South Korea mentioning wartime ‘comfort women’ at UN rights meeting A Foreign Ministry source said Tokyo has suggested to Beijing that Li also visit somewhere outside the capital to develop a deeper understanding of Japan. Abe’s national security adviser Shotaro Yachi may have brought up these plans in a meeting in Beijing last month with State Councillor Yang Jiechi, China’s top diplomat. According to a source close to Japan-China relations, Chinese Ambassador to Japan Cheng Yonghua has expressed anticipation over Li’s visit, telling a senior member of Abe’s Liberal Democratic Party late last month that a formal visit by Li “would hold great meaning for bilateral relations”. But the nature and duration of Li’s stay in Japan is still not guaranteed. China has to first give the green light to the trilateral summit. Japan’s overtures toward Li are in sharp contrast to its plans for Moon. Japan and South Korea are at odds over a 2015 agreement that the Abe administration says was meant to “finally and irreversibly” resolve the issue of the “comfort women” forced into Japan’s wartime military brothels . Did Beijing just give South Korea's Moon the cold shoulder? But the Moon administration argues that Japan needs to do more than stipulated by the 2015 agreement, which was negotiated under Moon’s impeached predecessor Park Geun Hye. The three countries have been rotating summit-hosting duties since 2008, although a chill between Japan and China over the Senkakus put a stop to the gatherings in 2013 and 2014. After South Korea hosted a trilateral summit in 2015, Japan planned to do so in 2016 but dropped that plan in light of the political turmoil enveloping Park.