Asami sexually assaulted Akihito the first time they met. And it's mentioned that he had sex with other men and women. Who’s to say he doesn't have any other victims?
This can actually be explained with Early-Installment Weirdness. Yamane Ayano admitted in volume side notes that Finder was created as a one-shot story for the theme Be x Boy GOLD was doing for that monthly issue. She didn’t expect the story to become as popular as it did, and it evolved into its own series. This is not to excuse Asami’s behavior in chapter one (and it seems like Yamane Ayano regretted how she did that chapter) but subsequent chapters demonstrated that Asami fixated upon Akihito and Akihito only. And subsequent Character Development showed that Asami wasn’t a serial rapist with multiple victims, but also showed that Akihito actually liked what Asami was doing to him (and only Asami). So this is really just the matter of a series evolving from a short that wasn’t meant to be a series to begin with.
