At that time there was a semi-express that would stop at Minamikata Station (Osaka Prefecture) and Sozenji Station, in addition to the express stops from Takatsukishi Station and to the west, but this train made a difference because, although it started making a stop at each station in mid-course, it went nonstop at these two stations, and therefore it was necessary to create an intermediate type between the express and the semi-express.
当時、高槻市以西の急行停車駅以外にも南方駅(大阪府)・崇禅寺駅に停車する準急が運転されており、途中から各駅に停車するもののこの2駅を通過するという違いが生じるため、急行と準急の中間の種別を設定する必要が生じたことが設定の理由である。