Journalistin, Aufnahmeleiterin & Filmemacherin
In Japan’s Edo period, many travellers passed through the Kiso valley © Sonja Blaschke | In Japan's Edo period, many travellers passed through the Kiso valley © Sonja Blaschke
In Japan's Edo period, many travellers passed through the Kiso valley © Sonja Blaschke

ZDF Terra X:
Vergessenes Wissen – Das Erbe der Ahnen

Japan’s Edo period (1603 – 1868) was a time when almost nothing went to waste – not even human waste. In fact, the excrement of wealthy households was particularly sought after as fertiliser. What can we learn from Japan’s remarkably resourceful past?

Terra X is the flagship documentary brand of ZDF, Germany’s national public-service broadcaster. Known for its high-quality productions, Terra X covers a wide range of subjects, including history, archaeology, science, nature and culture.

Shot in 2025 across the world and broadcast in 2026, the Terra X series Forgotten Knowledge (Vergessenes Wissen) explores how traditional practices from around the globe can offer solutions to modern environmental challenges. From centuries-old architecture in Spain and traditional fire management in Canada to sustainable fishing in Europe, the series shows that sustainability is far from a modern invention.

For the second episode, The Legacy of Our Ancestors (Das Erbe der Ahnen), we travelled back in time to explore Japan’s sophisticated recycling culture. Old fabrics were repurposed into clothing (sakiori), rice straw was turned into sandals, and even human excrement was collected and sold as valuable agricultural fertiliser. These practices formed part of an elaborate circular economy in Japan long before recycling became a global concern.

Our guide through Japan’s Edo-period recycling culture was Kyota Ko, an author and content creator specialising in Japanese history and folklore. Known for his entertaining books and popular Instagram account @themetroclassic, he brings Japan’s past to life through fascinating stories and often surprising historical details.

Illustrating Japan’s Edo period: on location in Tsumago-juku in the Kiso valley © Sonja Blaschke | Illustrating Japan's Edo period: on location in Tsumago-juku in the Kiso valley © Sonja Blaschke
Illustrating Japan’s Edo period: on location in Tsumago-juku in the Kiso valley © Sonja Blaschke
Traditional architecture on the verge of dying out in Japan © Sonja Blaschke
Traditional architecture on the verge of dying out in Japan © Sonja Blaschke

For this project, we spent several days in Tokyo and its vicinity, but also several days in the picturesque Kiso valley in Nagano prefecture. As the line producer for Japan, I was responsible for researching and scouting filming locations, finding and casting protagonists and experts, arranging interviews, securing filming permissions and coordinating production logistics, including liaising and interpreting throughout the shoot.

Production & Broadcast Details:

Series: Forgotten Knowledge (Vergessenes Wissen), 2 × 44 min
Episode: The Legacy of Our Ancestors (Das Erbe der Ahnen), Episode 2
Written by: Cristina Trebbi, Susanne Utzt
Directed by: Christopher Gerisch, Anja Kindler, Jobst Knigge, Cristina Trebbi
Production: SPIEGEL TV
Broadcaster: German public broadcaster ZDF / Terra X
Cinematographer (Japan): Francisco Lopez
Line Producer (Japan): Sonja Blaschke
First broadcast: 26 April 2026, 7.30 pm, ZDF

Watch (in German) on ZDF’s streaming platform (Japan segment: 01:30-08:00):

zdf.de/video/dokus/terra-x-vergessenes-wissen-100/terra-x-vergessenes-wissen-da…