Her name is Rin Takeyami. Don't go looking for any meaning in that name. Rin is a name I like. Takeyami was just a name that popped into my head. Maybe it is a reap Japanese surname, maybe not. Maybe it holds actual meaning in Japanese, maybe not. I wouldn't know. It came into my head and seemed right, so regardless of whether it's a real Japanese surname or not, it at least sounds like a Japanese surname (so, yes, explicitly As Long As It Sounds Foreign), thus, it's her name.
She's Japanese-American, with her parents having raised her in America her whole life, though she is bilingual (though because I'm not, this'll only show up in occasional foreign cursing) and knows of her father's country's customs. Her father is often away on business, and her mother passed away when she was fifteen (or thereabouts), so she's mostly home by herself, thus, how she encountered Ruby. (She's home-schooled partially, attending the same school as Ruby.)
I do invoke a bit of But Not Too Foreign, because she looks mostly Caucasian, but in my experience with people of mixed heritage, this isn't actually that unusual: they mainly seem to take from the gender of their parent. For instance, one family I've met had two sisters that look exactly like their Asian mother, yet have a brother who looks almost exactly like his Caucasian father. (To the point where people often ask if he, or they, were adopted, when no, that's just how it turned out.)
She is a lesbian, which is something that wouldn't please her father normally, but while her mother was still alive, she managed to make a very persuasive argument to her father that basically left him being okay with it, even if it isn't what he would have wanted. (Basically, she points out in America, women are to some extent expected to be strong and independent, and she could succeed him in their family business, arrange for an heir, and continue the family name...OR, she could disown him, go off on her own, and still make a name for herself anyway.)
I kinda like her.
(...Since she's Ruby's love interest, I, uh. Kinda need to specify that I like her as a character.)