The photo is from an event in October 2005. Here are links to another event, and to her first public appearance: being presented as a new seiyuu by I's Entertainment, which also represents Saitou Chiwa, Nakahara Mai, and others. It's a changing news page, so you make have to look lower or search. On 2channel, there is a "Yahagi Sayuri support thread."
Here is a rough translation of an interview from late summer 2005:
Interviewer: You're just about to start recording Karin. How do you feel?
Yahagi Sayuri (YS): Umm, half happy and half nervous.
What were your feelings when you were given the role?
YS: “No way!!!” (laughs) I thought they were kidding me. Then during a call from the agency explaining things, I began to realize: “Oh, it's really true.” At first, it didn't feel real at all.
Tell us about the character Karin.
YS: Karin is a “blood-giving vampire,” but she's also a shy ordinary girl. Her emotions really came out in the original manga when I read it. You honestly just wanted to help her because she seemed so cute and vulnerable.
Do you have anything in common with Karin?
YS: Karin is clumsy, and I'm also a bit clumsy....(laughs) Sometimes I fall over for no reason at all. And in general I'm a pretty happy person.
And are there ways in which you're definitely not like her?
YS: Well, I don't bite people (laughs)! And I've noticed how nice Karin is to people. That isn't so much something where I'm not like her as something in her that I'd like to imitate.
Karin is your debut role. What made you want to be a voice actress?
YS: Because of my high voice, in elementary school my friends called me “Burikko” (kiddy-girl, child-like woman). It was really mortifying. But I thought: “Someday I'll get back at you.” It was in my second year of middle school (grade 8) that I first learned there was such a job as “voice actress” and wondered if I might be able to make use of the voice I had such a complex about. That challenge was my impetus to becoming a voice actress. Up until then, because I liked drawing, I wanted to be a mangaka.
A mangaka! So you liked manga and anime even then?
YS: I especially loved Sailor Moon. We used to play Sailor Moon all the time. I had no idea at all that one day I would become a voice actress myself (laughs).
What kind of voice actress do you want to become?
YS: I want to be someone who never betrays the people who watch something I do, a voice actress about whom they can say: “Yahagi Sayuri is really good in this role.”
Finally, do you have anything you want to say to people?
YS: I'm going to do my utmost to get closer and closer to Karin's feelings. I want to do everything I can to have Karin and I grow up together. Please give your support to Karin, everyone.