Through waking up and getting ready for the day, you couldn't help but feel like you were forgetting something. You check you're mail and see a letter from Heizou! Yes, that's right, it's his Birthday! The letter reads:

"Even on a day like this, your ever-vigilant Doushin Shikanoin remains on duty, patrolling the bustling streets of Hanamizaka. And wouldn't you know it — just as I was passing by, the crackling of sizzling oil reaches my ears. A sign, perhaps? Looks like today's "surprise case" left behind some decisive clues the moment that hot oil began to fly. I conducted a thorough investigation which may have included a "taste test" or two, and successfully secured the prime piece of evidence: one caramel-crusted katsu, dipping sauce included. If I remember correctly... this happens to be your favorite flavor. So, now that you're holding this letter, what do you say? How about lending me a hand in closing the case? I could really use a sharp-eyed witness like you to help wrap up this birthday surprise. And hey, don't worry. No interrogations. No paperwork. No need to bring anything... Just show up hungry."