For several centuries, the inhabitants of Terra-Earth have expanded into space with the discovery of warp-naviagtion. As a rsult, numerous planet nations have emerged and humans have met inhabitants of other systems. Even with the cycles of war and peace, various planet nations signed the Interstellar Alliance Treaty and a peaceful co-existance in space has been achieved.

The Cosmo Academy was established 120 years ago to usher in the new era. This institution has the finest space science facilities and exists to educate many leaders of and for the future. Applicants from Terra-Earth and other stellar nations have come to join the Cosmo Academy.

These applicants leave for a final test in groups of ten, but when Tada\\\\\\\'s group arrives on the Esperanza, there is something they find out in horror: there is an eleventh member of the group. Who is the eleventh member and what is this member\\\\\\\'s purpose?