Also known as "The Riddle of Tsukikage Castle."
At the end, Zenigata starts throwing coins in the manner of his ancestor, the famous literary detective Heiji Zenigata. Lupin takes notice of this in the original Japanese language version.
In the original Japanese audio, Lupin declares the view from the hotel room a "masterpiece" and strikes a kabuki pose, echoing a famous line from Kinmon Gosan no Kiri, which is appropriately a play about Goemon Ishikawa, the ancestor of our Goemon.