Regional climate system in East Asia shows the characteristic seasonal cycle affected by the Asian monsoon with various types of its sub-systems. The seasonal cycle there is also related greatly to behaviors of the frontal zones which are the boundaries of these sub-systems. Since the variation of global-scale environment such as the global warming influences on each monsoon sub-system in rather different manner, it is necessary to understand the joint effects of these subsystems, in order to predict the regional climate change in East Asia in the global warming. In such research, it would be also useful to examine the features in the ice age, as an opposite extreme situation against the global warming. Thus the present paper will discuss some viewpoints in investigating the regional climate in the Last Glacial Maximum with attention to the seasonal cycle and daily meteorological systems.