Your device should have the acceleration sensor.
How to play:
When displays on the screen, "Ready", you grip your device and punch continuously for 20 seconds.
Don't play if this is larger than your hand.
I think it is effective in the shape-up of the upper arm.
You must not play toward someone.
The Developer doesn't take the responsibility at all even if you hurt someone.
Don't release this from your hand intensely punching too much.
The Developer doesn't take the responsibility at all even if this breaks something or this breaks down.