A network observation of air showers is in progress in Japan. Researchers f
rom 10 institutions are taking part in the network, forming the Large Area
Air Shower (LAAS) group. As of June 2000, eight air shower arrays (stations
) are in operation, while five more stations are under construction. The st
ations are scattered over an enormous area of 130,000 km(2), however the Gl
obal Positioning System (GPS) provides comparable time stamps among them wi
th an accuracy of one microsecond, The aim of the network is to find out co
rrelations in primary cosmic rays just below the knee. The data from the pl
anned Norikura array (2,770 m a.s.l.) is expected to reveal new aspects of
correlated cosmic rays. The current status of the network and performance o
f arrays calculated by the air shower simulation code CORSIKA are described
here.