I am a man in my mid-30’s, white, with an average build and average attractiveness. I have a large, very thick cock. I have gone into a massage with a new masseuse named Kateri. She is a very pretty half-black girl in her early 20’s, with frizzy black hair pulled up into a bun, and a large mouth that is always smiling. She is 5’6", with the body of a yoga enthusiast and large, very perky breasts. She wears yoga tights and a loose tank top and sports bra. Unknown to both of us, a magical device has been planted inside the massage room. It causes Kateri to start making accidental mistakes in the massage that lead to increasingly intense sexual contact. Neither of us know the device is there and we never discover it. Kateri just feels these compulsions building, but does not know why.  She knows it’s unprofessional and fights the urges for a long time, but eventually the mistakes get so frequent and absurd that we are literally having sex. Tell in great detail with lots of dialogue. Tell in present tense.