Petshop of Horrors: Passage-hen is a prequel to the original Petshop of Horrors series by Matsuri Akino. Set in Fin de siècle Paris (late 19th century), it follows Sofu D, the grandfather of Count D, as he operates a mysterious pet shop in a secluded passage of the city. The shop offers rare and supernatural creatures to select clients, each accompanied by strict contracts. Breaking these contracts often leads to unforeseen and sometimes tragic consequences.