One day, Chise, a book-loving and curious boy, finds a small child named Soichiro collapsed on the street at night and takes him home. However, Soichiro suddenly licks Chise's blood and transforms into a fine adult man. Chise's body goes into heat as a side effect of his vampirism, but Soichiro nonchalantly comforts him as a "thank you."

"Will you leave me here?"

The price is the story of the days they have lived for a long time. For Chise, it is more appealing than anything else.