Eien (永延) was a Japanese era (年号,,nengō,, lit. "year name") after Kanna and before Eiso. This period spanned the years from April 987 through August 988. The reigning emperor was Ichijō-tennō (一条天皇).
January 2, 987Eien gannen (永延元年): 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 Kanna 3, on the 5th day of the 4th month in the year 987.