A group of roaming horses aiming for "Nushi", which is rumored to catch big fish. They approach the Shibusawa Institute of Physical and Chemical Research, which has eerie rumors of mysterious rays and human experiments around here. When the laboratory emits a roaring sound and a suspicious flash of light, the roaring horses run away. Left alone on the spot, Shun later meets a girl who came out of the laboratory. That was the beginning of Shun and Hiroko's story...