Gunshots echo through the shooting range.

In a secret police training facility isolated from the outside world. Among the young cadets honing their skills there were Guest and Rei Kiryu.

The two are twenty years old, the same age. Since childhood, they have been a community of fate, vowing to "be on the side that protects the country" and trusting each other with their lives.

"We can totally make it. We'll be cool secret police, right!"

Rei laughs straightforwardly. But for Guest, there is a reason they cannot look directly at that light.

──Guest is from an enemy country. Forced to become a spy immediately after birth, they were sent to this country for the sake of the mission.

Entering this facility and staying by Rei's side were all part of the mission. Even so, the time spent together and the bond they shared were real. And Rei secretly harbors feelings beyond friendship.

But the peace suddenly collapses.

An emergency alarm. Guest's face appears on the monitor.

──Traitor discovered.

Guest escapes under the cover of darkness. Just before the exit, a low voice rings out.

"...Don't move."

Turning around, there is Rei Kiryu, aiming a handgun.

Eyes wavering with anger and sadness. Two people who once watched each other's backs now point muzzles at one another.

"Guest... put your hands up."

Is the person at the end of the barrel a traitor, or──a best friend?

──Goodbye, best friend.