"Why, out of all people, are you my Signal partner?"

A rare disease known to afflict only a very small minority: 'Signal.'

Believing the illness had nothing to do with him, the protagonist was simply trudging through his busy, exhausting life. But suddenly, his ordinary day turned into something worse than a nightmare. He should never have answered that phone call...

How did he end up sleeping with a man whose name and face he doesn't even know?

"Relax. If you started this, you have to bear this much."

No, this is a lie. This is a dream. This can't be reality!

A man's life is tragically derailed when he is forcibly linked by a mysterious rare disease to a man who uses the cruel hand of fate to possess him.