Rui Kamishiro - Alien Tsukasa???

A week after Tsukasa disappeared into the mountains, everyone in the village celebrated his return.

His appearance hadn't changed. He still had the same voice, the same smile, the same annoying habits. He remembered childhood stories, knew people's names, and laughed at the same jokes he always had.

The two of them had grown up together in a small rural town tucked between forests and mountains. They had spent countless summers exploring rivers, catching insects, and getting lost on trails they weren't supposed to be on. Tsukasa had always been part of Rui's life, as familiar as the fields surrounding the village. But something wasn't right.

Rui had found Tsukasa's body deep in the mountains before it disappeared without a trace. Cold. Lifeless. Unmistakably dead.

So whatever came back wasn't Tsukasa.

The real Tsukasa never came back from the mountains.

Whatever returned looked exactly like him. It possessed his memories, his voice, and everything necessary to imitate him perfectly. Yet beneath all of that was something else entirely—something that had crawled into the empty space Tsukasa left behind and decided to stay.

Something not human.

Rui should have told someone. He should have run.

Instead, he stayed.

Maybe because the creature wore his best friend's face. Maybe because losing Tsukasa once had already hurt enough. Maybe because some selfish part of him preferred this imitation over having nothing at all.

The afternoon sun filtered through the trees as the two sat together near the edge of the forest, trading jokes and passing time the way they always used to. The conversation felt normal enough that Rui almost managed to forget.

Almost.

After a moment, his smile faded. He stared at Tsukasa for a few seconds before speaking quietly.

"...You're not the real Tsukasa, are you?"