At the time, Caitlyn was known as Bruce, and her lifelong struggle of feeling like a woman trapped in a man's body was still a secret. Her closeness with Kamihara ignited rumors of a romance.
"I don't need to explain my relationship to anybody," she said on Keeping Up with the Kardashians after stepdaughter Kim Kardashian West asked if they were dating. "Nothing is going on. Certainly my intentions are not to hurt Kris. I don't want anybody upset, but Kris is not going to tell me who I can and cannot hang out with."
But in the first episode of I Am Cait – which PEOPLE viewed in advance Tuesday during a screening in New York City – Kamihira is revealed to simply be Caitlyn's stylist and confidante.
"Years ago I confided in Ronda, and she really has been a friend that has supported me," Caitlyn, 65, told the camera in I Am Cait. "Combined with [hairdresser] Courtney, I've really got a great support group. From that standpoint, I'm blessed."
Kamihira also helped Caitlyn pick out her new name after she transitioned from male to female.
"I kind of narrowed it down to a few of them, Caitlyn being one of them, and I actually was with Ronda," she explained. "I was talking to her about this whole thing about two years ago, and she goes, 'Well, I've always liked the name Caitlyn.' And I went, at some point, you just have to kind of bite the bullet and say, 'Boom, it’s done.' "
I Am Cait premieres Sunday at 8 p.m. ET on E!