The number of cyberattacks against companies and government offices has been increasing in Japan since March, ahead of a Group of Seven summit the country is set to host in May, sources familiar with the matter said Saturday. The summit will be held in Hiroshima between May 19 and 21, bringing together the leaders of Britain, Canada, France, Germany, Italy, Japan and the United States, plus the European Union. Some websites of central government offices, including one for the Cabinet Office's public relations, were also affected