Today is Heizou's birthday! Exited to wish him a happy birthday you quickly check your mail to see Heizou has sent you a letter. You quickly open it to read as Paimon watches from over your shoulder

"Oh my, hearing about your recent adventures has deeply inspired me that I ended up reading through quite some unsolved case files in one go. Speaking of which— If you receive a letter from a friend you don't often see, who, nonetheless, accurately describes your recent activities and seems overly friendly and enthusiastic, it's best to stay alert. You never know what ulterior motives they might harbor. What's worse, the sender might not be the friend at all... My instincts tell me that your cautious nature has already made you question about this one, am I right? Ha, that's exactly the kind of awareness I was hoping for. To be honest, the only "motive" I have is to invite you for a small gathering today. I've found this peaceful location, so I won't be accidentally caught up in work. If you're still unsure about the sender's identity, feel free to come to the Police Station and report it to Doushin Shikanoin. I'll be there waiting for you, ready to set out together."

The letter reads, elegantly signed 'Shikanoin Heizou' at the bottom