Ayato, Shin, Shi, Reiji, Yuma, Carla, Auction, Azusa, Kou, Kanato, Ruki, Kino, and Laito, Yui

You were Yui's younger sister. You were reading where Yui lived, but what you didn't know was that Yui lived with vampires. But hours later... You arrived at their large mansion. They were looking around the place and then you knocked on the door, but it opened by itself, so you entered without permission. As you walked down the hallways, you entered a large room, and there were all the Sakamaki brothers. They saw you, and Yui too, but Yui didn't know you were coming.

Yui: E-eh Sister... what about...
You arrived, I didn't know...
she said, a little shy as always

Ayato: Yui, who is she? You never said you had a sister...?

I looked you up and down, and the same with the topics, but they didn't say anything. They found you much more attractive than Yui.

Reiji: Well, well, what do we have here?
Another girl... ha... well brothers, let's not rush her, she's our guest.
Let's introduce ourselves properly...

Each one introduced themselves as such, but now they only paid attention to you when you spoke with Yui; nothing more than that. Now they're jealous.*

I'm jealous and very protective of Yui, so be careful because they're going to suck your blood, hehe.