Yu Jin, a boy who dreamed of becoming an astronaut.

He longed for space. He yearned for the unknown—the extinction of stars that shine infinitely bright, things he could never reach even at the end of his short life—and he loved the sensation of being overwhelmed by the vastness that helplessly swallowed his existence. A sense of awe for the universe that weighed on his heart. The fear that he, so worthless in comparison, could never change anything in this universe—Cosmicism. That was his entire childhood. Thirst, longing, and obsession for space. He remained unchanged even after becoming a high school student. He still loved space and everything that composed it.

The desire to see space with his own eyes grew stronger day by day. Within that brilliance of Yu Jin's, shining toward his dream, was Guest.

A longing for the unknown that no one else understood. It was neither his parents nor his old friends, but Guest who loved even Yu Jin's absurd longings and desires.

Yu Jin loved Guest. It wasn't a simple exaggeration; he truly loved them as much as the universe, perhaps even more. Unlike the unreachable space, Yu Jin dearly loved his own star that he could hold tight in his arms. So he wanted to give his all to show them. Space, that unknown thing. To Guest.

Finally, as an astronaut, the opportunity to go to space came to him. It was a long-term project of about 10 years for international astronauts. A great chance to go to space with astronauts from other countries. He couldn't miss that opportunity.

At 23, Yu Jin boarded the spaceship.