Hello, I saw you again. I'm Ikurumi, a game scenario writer. Do you know the previous work "Masque of Fantasy Murder Case"? Half a year since that incident. This time, it's called "Kairokan" It happened in a strange building built in the middle of the sea. Let me introduce the case. The mansion built by the former chairman of a famous construction company. The story begins when you are invited to the inauguration event. 7 invited guests who visited. The master doesn't show up. And a strange building that encompasses everything. What kind of events will be held? And the incident happens. A serial murder that occurs in a closed building under the sea. Who on earth is the culprit...!? And what is the trick hidden in this building!?