Inshitsu Otaku ni Ikareru Kanojo

For years, Shuji Mizuhara has kept buried his complicated feelings for his younger sister Saki — until Saki confesses she feels the same way, and what should be a quiet, relieving moment instead opens the door to something much darker. Shortly after they grow closer, an anonymous email arrives with compromising photos of Saki attached. Someone has been watching her. The stalker doesn't want money — they want control, forcing Saki into increasingly uncomfortable situations while Shuji tries to figure out who's behind it and how to protect her. This 3-episode OVA from Studio 9 Maiami leans into psychological tension more than most entries in the genre. The setup is less about the relationship itself and more about the dread of being watched and coerced — there's a genuine thriller undercurrent running through it. The character animation holds up well, and the soundtrack actually does some work in building atmosphere rather than just filling silence. If you've watched Boku no Yayoi-san and appreciated when these productions bother to build emotional stakes before diving in, this scratches a similar itch. Fans of Oni Chichi who want something with a bit more narrative tension rather than pure setup-and-scene structure will find this a step in that direction. It's based on a visual novel, and that source material shows — there's more character groundwork here than you'd typically expect from a 3-episode OVA. Worth a look if psychological friction alongside the adult content is what you're after.