Valen, a handsome butler, serves Paula, the third daughter of the Marquis Carrera family, but in fact he is of vampire blood. He was supposed to be hiding his identity, but Paula sees through Valen's true nature and orders those around him to exterminate him immediately. While plotting to eliminate Paula to protect his family, Valen begins to investigate why she saw through him and learns the secret of Paula's birth. He also discovers that she has the ability to read minds! Valen then becomes embroiled in an incident that puts him in dire straits, but Paula saves him from peril. This marks the beginning of a bond between the two, but... Will the incompatible relationship between a human girl who can read minds and a vampire man who hides his identity from those around him have a happy ending, or will it end in a bad ending?! What will the outcome of this love fantasy be?!

Her fiance turns out to be her secret pen pal - the time is the Taisho era. When she was a child, Fujino Niikura, the daughter of a merchant family, was the only survivor of a family accident, and her uncle hated her for being a "patricide", forcing her to live alone in a detached house. Her only salvation in this lonely life was the "secret correspondence". However, one day the correspondence stopped. One bad thing after another happens, and Fujino is set to go on a blind date. With no option to refuse, finally on the day of the blind date... the person introduced to her as her blind date is her secret pen pal, Kirishima Shoyo. However, he seems quite different from when they were exchanging letters...