Keiichi is a biology student and a pupil of Professor Yodogawa, a researcher who studies the mysterious creature that destroyed Asa's home. In 1959, he goes on an expidition with Yodogawa where they discover a claw mark left by the monster. In 1964, he meets Asa while transporting all of Yodogawa's research on the monster. He is tasked with deciphering Yodogawa's findings to discover as much information on the creature as possible.