Betraying her sister. The sister who slept with her older sister's boyfriend was involved in an NTR (Netorare) sex act, which was secretly filmed and then sold without authorization. SIM-110

As the older sister, I'm often away for work. When I come home, I find my live-in sister behaving strangely, and the room smells weird... When no one's around, I secretly install a hidden camera in the house and end up watching my sister having sex with her boyfriend...