Rittai Poruno-Sukoppu: Sentensei Roshutsukyou (1973)

Presumably inspired by Pete Walker's 4 Dimensions of Greta this is another 1970s sex comedy filmed in 3D. Walter Boos however went all the way - we do not have just the odd 3D boob scene, the whole film is made in 3D. The viewer is constantly reminded of that, because the cinematography is truly bizarre with plenty of scenes of rather peculiar camera angles that strongly emphasize the 3D effects, e.g. a girl on a swing moving towards (and above) the camera, twigs hitting a car window, and many many more. The exaggeration of 3D makes these scenes quite funny, as the effects are completely over the top.