The Poe Clan

(from ebookjapan):

Around 1880, the Baron de Portsnell and his family visited a seaside town. They had come from London, and they soon became well known in the city. The baron and his wife and their children, Edgar and Marybelle, exuded an elegance that was out of place in a country town.

The sight of them was like looking at a perfect painting. In fact, their beauty was a magical beauty out of time. They were the "Poe's Clan", vampirnellas who consume human blood. The family rented a house on the outskirts of the city and began to search for someone to welcome into the clan, pretending to be human.

Edgar was intrigued by Alan Twilight, the son of the city's foremost trader....

Official English

• Won the 21st Shogakukan Manga Award for Shojo in 1976, which it shared with Hagio's other serial, They Were Eleven