Pet Shop of Horrors - Hyouhaku no Hakobune-hen

Takes place before the events in Petshop of Horrors, with D's grandfather as the protagonist.

A smoke-filled alley in Chinatown harbors Count D's Pet Shop. The pets sold here aren't your everyday variety and the Count prides himself on selling Love and Dreams in the form of magical creatures that come with an exclusive contract. But buyers beware. If the contract is broken the Count cannot be held accountable for whatever may happen. A fascinating and macabre look into the very soul of human nature.

(Source: TOKYOPOP)