Saejima Nao: Kankin

Original title: 冴島奈緒　監禁

Marina, an up-and-coming lingerie designer, is in a lesbian relationship with Saki, an underwear model. However, a man becomes attached to Marina and her underwear and succeeds in eavesdropping on her room. He listens to her vivid secret life every night, but that's not enough for her...