Slut Classroom (2000)

In the late-night park, couples entwined—a faint shutter click echoes through the darkness. For Ryoji (Kawai Makoto), hunting for photos to sell for pocket money, they're perfect targets tonight. The next day, Ryōji finds himself suddenly captivated by one such subject. The scandalous woman captured in the shot bore an uncanny resemblance to Shizuka (Ami Minami), the high school teacher he had once admired.