The night sky appears to be quiet and stable, but in reality many explosive events are happening in the universe every night. Such events are now being caught efficiently with recent transient surveys, and rapid follow-up observations are revealing exciting nature of these explosive events. In this talk, we present our follow-up observation activities of interesting transient events. These studies cover a wide range of astronomoical events including Swift J1644+57, the moment of a supermassive black hole devouring a star, the Chirstmas burst, a peculliar GRB caused by a death of two stars colliding in a common envelope, and GRB 071025, an explosive stellar death at z ~ 5 which reveals the existence of SN-dust in the early universe. In addition, we also present our work on a very nearby supernova in M101 galaxy which occured very recently. These and future transient events will continue to show us fresh views of the universe.