The protagonist is Canaan, the second prince of Loukios kingdom, a small country in the Free Cities Alliance. He didn't have a special training, so he has the strength of any average boy. One day, an adventurers guild is formed. They want to break the seal of a labyrinth that was closed a long time ago. Then, Canaan and his servant Celeste join the adventure... [Translated from [url=http://es.wikipedia.org/wiki/Oujisama_Lv.1]Spanish Wikipedia[/url]]

Ouji-sama Lv1.5 is a collection of smaller games based solely on Ouji-sama Lv1. It's akin to Alicesoft Alice's Cottage. The main game is called "Ouji-sama 1 month after" and is set one month after the events of Lv1. The story revolves around Celeste Irving's family and the conflict between Adolphe Irving and his soon-to-be son-in-law.