, also romanized as Ō-an, was a Japanese era name (年号, "nengō", lit. year name) of the Northern Court during the Nanboku-chō period after "Jōji" and before "Eiwa." This period started in February 1368 and ended in February 1375. The pretenders in Kyoto were and The Southern Court rivals in Yoshino during this time were and .