High schoolers Mio Miyamasu and Arata Kishimo are childhood friends. Mio harbors feelings for Arata, but she lacks the courage to express them. Even when her friend Madoka asks if she is in love with Arata, Mio reluctantly declines and encourages her friend to pursue her own feelings for him instead. Later, while Mio and Arata visit a fortune-teller, the boy notices a strange phenomenon and tries to drag Mio out of the shop—much to her annoyance. As Mio begins to question her relationship with Arata, an argument erupts between them. That night, feeling guilty for what had occurred, Mio ventures into the rain to apologize to Arata and make her feelings clear. However, an accident along the way turns Mio's world upside down.

The great detective Holmes does not solve mysteries or use deductive reasoning. He does, however, hunt vampires. Using three-minute episodes, Vampire Holmes retells the story of the great Holmes and his assistant. What begins as an ordinary detective agency takes a turn for the occult when the Metropolitan Police of London secretly hire Holmes and Hudson to investigate vampires. Or at least that's what Holmes would tell anyone who asks. In reality, he and Hudson spend most of their time sitting around arguing, and failing to solve any cases. Joined by the not-so-black, demon cat Kira, and their terrifying rent-hungry landlady, this is the story of the man who was most definitely not London's greatest detective.