1. China and Japan 'normalized' their relationship in 1972. However, "Japan never apologized for the suffering of Chinese (300 million Chinese killed) during the Japanese invasion and occupancy", as complained by many Chinese. Former Japanese Prime Minister Tanaka Takuei (1972-1974) recalled he expressed 'being puzzled "困惑"' by what Japanese did to Chinese when he signed the 'normalization treaty' in Beijing. Tanaka argued the Kanji characters 'being puzzled' has a deeper meaning of 'not agreeing'.
2. Japanese Prime Minister Koizumi Junichiro (2001-2006) is known for his family roots which are entangled with the past glory of imperial army, and unapologizing attitude on Japanese's aggressions during the WWII. Unsurprisingly he was not popular among Asian neighbors, particularly China and Korea. For a while, China suspended talks with him. During an international meeting, Koizumi suddenly showed great interest in Chinese Premier Wen Jiabao's pen, and asked for a look. The two talked briefly, and the incident was considered a breakthrough in Sino-Japan relations.
3. The Sino-Japan relationship was once again frozen after the incident of Japan detaining a Chinese fishing boat captain near the Diaoyu Islands, which is controlled by Japan while claimed by both mainland China and Taiwan. In retaliation, China announced a suspension of bilateral communication of minister level and above. When the senior officials of both countries were attending an international conference, Prime Minister Kan Naoto (2010- ) caught up with Chinese Premier Wen in the hallway, and chatted for 20 minutes. According to reporting of Japanese news media, the incident was 'executed in the manner of' while Wen walked out of the meeting room, Kan walked "in high speed in same direction" and caught up with Wen. It is assumed Wen slowed down. Japanese coverage varied on the account whether Kan walked in big steps or small steps, but agreed on the 'high speed' part.