Kōan (弘安) was a Japanese era name (年号,,nengō,, lit. "year name") after Kenji and before Shōō. This period spanned the years from February 1278 through April 1288. The reigning emperors were Go-Uda-tennō (後宇多天皇) and Fushimi-tennō (伏見天皇).
1278Kōan gannen (弘安元年): The new era name was created to mark an event or a number of events. The previous era ended and a new one commenced in Kenji 4.
Events of the Kōan era
1287 (Kōan 10, 10th month): In the 14th year of Go-Uda-tennō 's reign (後宇多天皇14年), the emperor abdicated; and the succession (‘‘senso’’) was received by his cousin. Shortly thereafter, Emperor Fushimi is said to have acceded to the throne (‘‘sokui’’).