Diet sessions: 177th (regular, January 24 to August 31), 178th (extraordinary, September 13 to September 30), 179th (extraordinary, October 20 to December 9)
January 26 – Shinmoedake volcano erupts in Shinmoedake and the surrounding areas, continuing until no earlier than March 10, in southern Kyushu Island. [citation needed]
March 9 – Takeaki Matsumoto is sworn in as the Foreign Minister of Japan, replacing Seiji Maehara who resigned following a political donations scandal.[8]
March 23 – The Grand Bench of the Supreme Court rules that voting weight disparity in the 2009 general election for the House of Representatives was in an unconstitutional state.[12]
March 31 – The Grand Prince Hotel Akasaka was due to be closed on this date, but remained open through June 2011 to house people displaced by the earthquake, tsunami, and nuclear alert.
May 4 – Osaka Station City, the largest enclosed shopping mall in Japan, including a cinema complex, a department store, and commercial facilities, opens in Osaka.[citation needed]
May 10 – GoExPanda becomes Mascot of TV Asahi in Tokyo.
May 12 – Worst heist in Japan: 604-million-yen robbery, in which a 36-year-old security company's workers are injured in Tachikawa, Tokyo. Six men are arrested on suspicion the heist on July 31.
October 26 – Tsuyoshi Kikukawa resigns as the President and Chairman of Olympus Corporation, as financial and law enforcement bodies in Japan, the United States and the United Kingdom investigate the optical equipment company's acquisitions in recent years.[15]
November 13 – 2011 Miyagi prefectural election (originally scheduled for the unified elections but postponed following the Tōhoku earthquake): the LDP loses some seats, but remains strongest party with 28 of the 59 assembly seats.
November 20 – 2011 Fukushima prefectural election (originally scheduled for the unified elections but postponed following the Tōhoku earthquake): With many voters displaced by earthquake, tsunami and nuclear accidents, turnout reaches a historical low at 47.5 percent; the LDP gains one seat and now holds 27 of the 58 assembly seats.
November 27 – 2011 Kōchi gubernatorial election (uncontested): With explicit or implicit support of all established parties including the Communists, governor Masanao Ozaki is reelected without vote for a second term – the first uncontested gubernatorial election since Yoshihiro Katayama's reelection in Tottori in 2003.
November 27 – Double election in Osaka: Major issue of both the 2011 Osaka gubernatorial election and the 2011 Osaka city mayoral election were resigned governor and mayoral candidate Tōru Hashimoto's Osaka Metropolis plan to dissolve the cities of Osaka and Sakai and reorganize them like Tokyo's wards as special wards of Osaka prefecture. Incumbent Osaka city mayor Kunio Hiramatsu was opposed to the plan and was supported by both major parties; even the JCP nominated no candidate for Osaka mayor for the first time since 1963 to support his reelection. Despite support from all established parties and all other candidates dropping out of the race, Hiramatsu lost the mayoral election to Hashimoto by a wide margin; and Hashimoto's candidate for governor, Ichirō Matsui comfortably won the gubernatorial race against Kaoru Kurata (both major parties), one Communist and several minor independent candidates (including perennial candidate Mac Akasaka).[16][17][18][19]
