The story concerns a girl who suddenly appears in front of Nagi Tsukuba, the protagonist, claiming to be the incarnation of Nostradamus' The Prophecies. She claims that it is somehow his fault that the world did not end in July 1999 (as supposedly predicted in century 10, quatrain 72), and that Nostradamus, being extremely bothered by this, has sent her to prove to Nagi that the prophecies are to be respected. (Source: Wikipedia)