Vampire Sweetie

In a certain quiet place on the outskirts of town, near the sea... Yuri worked as a caretaker of a white-walled mansion atop a hill in her father's absence.

One day, her father gave Yuri a phone call. Upon agreement after a business negotiation, her father had invited the business partner's sons to the mansion. Though angered by her father's selfish decision, Yuri liked the idea of a lively home so she had high hopes for the new residents.

Four good-looking brothers had appeared before Yuri.
The eldest Faust, who had a slightly suspicious aura.
The second eldest, Mikhail, who was refined and taciturn.
The friendly and cheerful third eldest Alon and youngest Joshua.

While Yuri was nervous because she didn't have much experience with men,
she was still able to get along with the brothers because of her naturally cheerful personality.

One sleepless night, Yuri was suddenly confronted by Joshua biting into her neck and sucking her blood. It turned out that the brothers were an advanced vampire family that weren't affected by sunlight, crosses or garlic.

Yuri was stunned.
Ordinarily, they had to kill those who find out their true identities but since they got along with Yuri so well, they made a suggestion:

"We won't kill you but let us suck your blood in exchange."

Aside from the blood-sucking, their lifestyles weren't much different from a group of good friends sharing a house. When they sucked her blood, they did so as considerately as possible, given that Yuri hadn't even held a guy's hand before. The sensation of their lips whenever they sucked her blood... The brothers held Yuri's blood in high regard, claiming it "very easy to drink".

Gradually, the darkness and past memories deep inside their hearts came to light.
And faint feelings shone from deep within her small chest.

From the moment Yuri realized those feelings were of "first love", the world had begun to change...

[Translation of official website plot summary.]