A bass drum, a snare drum, and cymbals were once all a composer needed to make a work sound exotic.
What police thought was a distressed cat turned out to be a man practicing the cuica, a drum which produces noise by rubbing a stick attached to the drumhead from the inside.
A normal person might spend a lifetime at it and still not succeed but faced with a determined Ren it was not greatly different from a normal cylinder lock.
The lock itself is a normal cylinder lock so it doesn't automatically lock when you shut the door.