but he just had to do a thorough cleaning after every use. A table clock showed it as past 11 PM. Before he could even think about who it might be at this hour, Kousaka’s smartphone, which had been charging on the desk, vibrated. He intuitively realized that the corresponding timing of the intercom and the email was not a coincidence. He picked up the smartphone and checked the new email. Open the door. I have no intention of hurting you. I want to talk about viruses. He looked up and glanced in the direction of the front door. His apartment wasn’t equipped with orthodox systems, and it was easy for intruders to enter the building without being tenants. The person who sent the text was likely already standing outside the room - at nearly the same time he realized this, there was a knock on the door. It wasn’t a rough knock, but a kind of knock that was for letting your presence be known. Kousaka stared at the phone in his hand, wondering if he should call the police. But the message displayed there gave him pause. “I want to talk about viruses.” He definitely had some idea about what that message could mean.