Completing the so-called “Classroom Trilogy” described by Children in the Classroom and Children Who Draw, Twins in the Class explores the scientific study of heredity and environment in child development through a behavioral analysis of identical twin sisters at the University of Tokyo Junior High School. Hani’s playfully breaks from his “signature” observational style by using a split screen to strikingly visualize the idea of the binary embodied by the twins.

Hani's deeply cinematic tribute to Japan's famous Horyuji Temple remains among the most visually striking documentaries in the history of Japanese cinema. Although Hani would later confess that filming the Buddhist statues in close-ups was far more challenging than filming human subjects, the montage of expressive faces that is the lyrical heart of the film offers a bristling poetry that immediately recalls Chris Marker and Alain Resnais' controversial short Les Statues meurent aussi (1953). Hani would later adapt the film's powerful soundtrack for his very different and best known work, Nanami: The Inferno of First Love.

After making a major name for himself as one of Japan's premiere directors of experimental art films, Hani returned to documentary in the mid-1970s and moved his operations whole-scale to Africa in order to film animals and nature. Part of a series of eight documentaries, Bravery offers moving portraits of wild animals struggling for survival that reveal Hani's consummate skill at capturing the spontaneity of wildlife. Hani's series of documentaries about animals became a great commercial success, broadcast widely and repeatedly on Japanese television.