Two Thousand an Hour: Twins Buy My Time

I, Sakakibara Isun, had my after-school hours bought by Mibu Kohaku for two thousand yen an hour. At first, the requests were nothing more than keeping her company, running errands, and helping her study. They never crossed the line, and ours was supposed to be a simple paid arrangement for fun. “It's so unfair to let only Big Sister monopolize Senpai!” Her younger sister, Mibu Ruiko, got involved. After that, the nature of our contract began to change a little.