Even in other worlds there are keys. There are many situations where lock-opening skills are useful, such as treasure chests in dungeons, hidden doors, and prisons. A freelance locksmith, Kii Jinroku (Rock), is scouted by the Thieves' Guild in this other world. Lock, who once trained under a master locksmith, uses his own skills to open locks in the other world! Taking on the fox-eared girl Ayla from the guild as his apprentice, Lock continues to take on key requests today...