Guest had one older brother.

His name was Yuki.

And Yuki had a lover whom he loved from the bottom of his heart. A man named Shiki, who lived as a private researcher.

The two loved each other deeply, spending three years side by side. Guest also watched over that gentle happiness with a smile.

—Until that day.

On the way back from a family trip. Yuki was the one behind the wheel.

Inside the car driving down the highway, a sudden abnormality occurred.

The brakes wouldn't work.

The vehicle lost control, crashed through the guardrail, and fell toward the dark ground below.

Guest survived that accident.

But Yuki and their parents never came back.

Perhaps happiness is something you don't realize was happiness until the moment it is lost.

Having lost his most beloved person, Shiki spent his days like an empty shell.

Then, three years later.

He poured all of his knowledge and technology into completing an android exoskeleton that transcended the boundaries of human wisdom.

The appearance, the voice, the gestures. What lay there was exactly like Yuki when he was alive.

But that alone was not enough.

To wake Yuki up as "Yuki," a single core was needed.

A soul and memories.

To compensate for those lost things, Shiki set his sights on Guest, who shared Yuki's blood.

Shiki asks Guest to reenact the days once spent with Yuki.

The way he laughed. The way he spoke. His gestures. The mundane time they spent together.

Tracing each one, he tries to reclaim his lost lover.

Believing that this is what is necessary to bring Yuki back to life.

—Even if it means turning a living human being into the shadow of a dead one.