Ummm. Where do you sign up to be her slave? This is definitely not what I thought was going to happen. Kinda too hot to handle. Reads like smut but with barely any ecchi.....yet. Guess we should prepare to get blue-balled every chapter until eventually there's some payoff? Oh god, I hope there's payoff.
Also, while I'm enjoying this quite a bit, I gotta point out that the "slave" bit is stupid. She obviously likes him and he obviously likes her. Obvious, as in the two of them should be aware of it too. I know he doesn't want to believe it since she's so popular but he heard her call out his name as/after she climaxed on HIS bed. And she was unbelievably embarrassed when she realized she was seen but he was jacking off to HER. They both have super clear indicators the other one likes them. It'll be awkward since they're step-siblings now but what they're doing now is gonna be so much more troublesome down the line.