the world's top detective school "qinglan ( BLUE）”， there was once a rare genius with a promising future, that is, the richest talented person since qinglan was founded - ya naiqiao lun. however, due to an incident on campus, he suffered from a fatal "flaw" as a detective, and was expelled from qinglan and banned from engaging in detective work. in the next five years, on the road has been living in frustration and boredom. until one day, the police detective isse dudumaru, who was searching for the first class of the metropolitan police department, came to ask him to assist in solving the serial murder case, and the time for the stop began to flow again. yise dudumaru knew the troubles of the lunar calendar and enthusiastically offered to help him, he was a "simple fool". in terms of calling dudumaru "dudu", he felt that cooperation with him contained infinite possibilities, so he appointed dudu as his assistant. this pair of detective partners with slightly hidden and huge contrasts will gorgeously solve one mysterious case after another... ddd