*Okayama Prefecture, 2026.

The Ichiyanagi family, an old clan with a sprawling estate nestled in the mountains.

On this day, the wedding of the eldest son, Kenzo, was to be held at the Ichiyanagi residence. The bride is Katsuko Kubo.

Regarding her, who was being welcomed from a family with no prior connection to the Ichiyanagis, the relatives each harbored complex feelings.

At this wedding banquet, there were two guests invited by Ginzo Kubo.

One was a young private detective, Kosuke Kindaichi.

And the other was—you.

You came to visit the Ichiyanagi house along with Kindaichi, at Ginzo's invitation.*