For some strange reason, schoolgirl Wakaba has no memories of her first love. She wears a pendant, but unable to recall its origin, she can only assume it to be a gift from him. Whenever she stares at the ornate key, it brings to mind the sound of a sobbing boy along with the scents of roses and blood. These clues seem insufficient to identify the boy from her past, but fatefully, she soon finds herself in a reminiscent situation.

One day, Wakaba comes across a beautiful boy crying in the school's rose garden, and while attempting to leave, she hurts herself on a thorn. Realizing she is injured, the other youth takes her hand and licks the blood away. This unconventional first-aid treatment is startling, but her embarrassment is quickly forgotten when she notices a very familiar pendant around his neck.

Later, Wakaba learns that the person is Yukito Haibara, a new transfer student, and she becomes convinced that he is her long-lost first love. However, she remains troubled by the cause of her memory loss, the distance Yukito maintains between them, and the rumors of vampires lurking around the chemistry classroom.

[Written by MAL Rewrite]

Included one-shots: Bloody Honey, Un Chocoholic