All his life, Riku Tachibana has been raised by his grandfather. For some reason, the old man has always had a fondness for strange hand gestures, which Riku has picked up and performs almost subconsciously, much to the amusement of his classmates. One day, however, it suddenly becomes clear to Riku what his grandfather has been secretly teaching him. And this knowledge could mean the difference between life and death for Riku.
