When you are in the middle of performing a concert, and some fella is just winding in front your face consistently to test your endurance. You might get mad, but not real mad, because you are dealing with some creature that is just a size of your palm.

The Japanese twitter user, @akatukisuwea was focusing on hitting every score note on the piano key while a video was recording, but suddenly, an uninvited guest appeared from the end of the piano key.

Then he came to the center..

Then he walked back,

Then he exited from the piano's front...

(The owner said his hamster somehow jail broke from his cage, gosh..)