1. Japanese Government

(General Information)
Prime Minister of Japan and His Cabinet
http://www.kantei.go.jp/foreign/index-e.html

(Food and water safety, Travel Safety, Reading of radioactivity level)
Ministry of Foreign Affairs
http://www.mofa.go.jp/j_info/visit/incidents/safety_info.html

(Water and Food Security)
Ministry of Health, Labor and Welfare
http://www.mhlw.go.jp/english/topics/2011eq/index.html

(Environmental radioactivity level for Air, Ocean Area, and Soil)
Ministry of Education, Culture, Sports, Science, and Technology(MEXT)
http://www.mext.go.jp/english/radioactivity_level/index.htm

(Airport and Port Security)
Ministry of Land, Infrastructure, Transport and Tourism(MLIT)
http://www.mlit.go.jp/page/kanbo01_hy_001411.html

2. International Organization

(Health Security)
World Health Organization(WHO)
http://www.who.int/en/

(Ship and Vessel)
International Maritime Organization(IMO)
http://www.imo.org/Pages/home.aspx

(Travel Information)
International Civil Aviation Organization(ICAO)
http://www.icao.int/

(Air Transport)
International Air Transport Association(IATA)
http://www.iata.org/whatwedo/industry-affairs/japan-measures/Pages/index.aspx

Nuclear Accident)
International Atomic Agency(IAEA）
http://www.iaea.org/